Mountain2/Manuscript/FCI2-SI.tex

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\documentclass[journal=jctcce,manuscript=article]{achemso}
\usepackage{graphicx,dcolumn,bm,xcolor,microtype,hyperref,multirow,amsmath,amssymb,amsfonts,physics,float,lscape,soul,rotating,longtable,tabularx}
\usepackage[version=4]{mhchem}
\newcommand{\alert}[1]{\textcolor{red}{#1}}
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\newcommand{\mcc}[1]{\multicolumn{1}{c}{#1}}
\newcommand{\mr}{\multirow}
\newcommand{\EFCI}{E_\text{FCI}}
\newcommand{\EexCI}{E_\text{exCI}}
\newcommand{\EsCI}{E_\text{sCI}}
\newcommand{\EPT}{E_\text{PT2}}
\newcommand{\PsisCI}{\Psi_\text{sCI}}
\newcommand{\Ndet}{N_\text{det}}
\newcommand{\ex}[6]{$^{#1}#2_{#3}^{#4}(#5 \rightarrow #6)$}
\newcommand{\pis}{\pi^\star}
\newcommand{\si}{\sigma}
\newcommand{\sis}{\sigma^\star}
% methods
\newcommand{\TDDFT}{TD-DFT}
\newcommand{\CASSCF}{CASSCF}
\newcommand{\CASPT}{CASPT2}
\newcommand{\ADC}[1]{ADC(#1)}
\newcommand{\AD}{ADC(2)}
\newcommand{\CCD}{CC2}
\newcommand{\CCT}{CC3}
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\newcommand{\FCI}{FCI}
% basis
\newcommand{\Pop}{6-31+G(d)}
\newcommand{\AVDZ}{\emph{aug}-cc-pVDZ}
\newcommand{\AVTZ}{\emph{aug}-cc-pVTZ}
\newcommand{\DAVTZ}{d-\emph{aug}-cc-pVTZ}
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\newcommand{\AVFZ}{\emph{aug}-cc-pV5Z}
\newcommand{\DAVFZ}{d-\emph{aug}-cc-pV5Z}
% units
\newcommand{\IneV}[1]{#1 eV}
\newcommand{\InAU}[1]{#1 a.u.}
\newcommand{\Ryd}{\mathrm{R}}
\newcommand{\Val}{\mathrm{V}}
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\newcommand{\SI}{Supporting Information}
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% addresses
\newcommand{\LCPQ}{Laboratoire de Chimie et Physique Quantiques, Universit\'e de Toulouse, CNRS, UPS, France}
\newcommand{\CEISAM}{Laboratoire CEISAM - UMR CNRS 6230, Universit\'e de Nantes, 2 Rue de la Houssini\`ere, BP 92208, 44322 Nantes Cedex 3, France}
\newcommand{\Pisa}{Dipartimento di Chimica e Chimica Industriale, University of Pisa, Via Moruzzi 3, 56124 Pisa, Italy}
\title{A Mountaineering Strategy to Excited States: Highly-Accurate Energies and Benchmarks for Medium Size Molecules\\Supporting Information}
\author{Pierre-Fran{\c c}ois Loos}
\email{loos@irsamc.ups-tlse.fr}
\affiliation[LCPQ, Toulouse]{\LCPQ}
\author{Filippo Lipparini}
\affiliation[DC, Pisa]{\Pisa}
\email{filippo.lipparini@unipi.it}
\author{Martial Boggio-Pasqua}
\affiliation[LCPQ, Toulouse]{\LCPQ}
\author{Anthony Scemama}
\affiliation[LCPQ, Toulouse]{\LCPQ}
\author{Denis Jacquemin}
\email{Denis.Jacquemin@univ-nantes.fr}
\affiliation[UN, Nantes]{\CEISAM}
\begin{document}
\clearpage
\section{Basis set and frozen-core effects}
\subsection{Cyanoacetylene, cyanogen, and diacetylene}
\begin{table}[htp]
\caption{\small CC3 vertical transition energies of cyanoacetylene, cyanogen, and diacetylene using various atomic basis sets.
FC stands for frozen core. All values are in eV.}
\label{Table-S1}
\begin{small}
\begin{tabular}{l|cccccccc}
\hline
& {\Pop} & {\AVDZ} & {\AVTZ} & \multicolumn{2}{c}{\AVQZ} & \multicolumn{2}{c}{\DAVQZ} & {\AVFZ} \\
& FC & FC &FC & FC & Full & FC & Full & FC \\
\hline
& \multicolumn{8}{c}{Cyanoacetylene} \\
\hline
$^1\Sigma^-$ &6.02 &5.92 &5.80 &5.79 &5.79 &5.79 &5.79 &5.79 \\
$^1\Delta$ &6.29 &6.17 &6.08 &6.06 &6.07 &6.06 &6.07 &6.06 \\
$^3\Sigma^+$ &4.44 &4.43 &4.45 &4.46 &4.46 &4.46 &4.46 &4.47 \\
$^3\Delta$ &5.35 &5.28 &5.22 &5.22 &5.21 &5.22 &5.21 &5.22 \\
$^1A''$[F] &3.70 &3.60 &3.54 &3.54 &3.54 & & & \\
\hline
& \multicolumn{8}{c}{Cyanogen} \\
\hline
$^1\Sigma_u^-$ &6.62 &6.52 &6.39 &6.38 &6.38 &6.38 &6.38 &6.38 \\
$^1\Delta_u$ &6.88 &6.77 &6.66 &6.64 &6.65 &6.64 &6.65 &6.64 \\
$^3\Sigma_u^+$ &4.92 &4.89 &4.90 &4.91 &4.91 &4.91 &4.91 &4.92 \\
$^1\Sigma_u^-$[F] &5.27 &5.19 &5.06 &5.05 &5.05 &5.05 &5.05 &5.04 \\
\hline
& \multicolumn{8}{c}{Diacetylene} \\
\hline
$^1\Sigma_u^-$ &5.57 &5.44 &5.34 &5.33 &5.34 &5.33 &5.34 &5.33 \\
$^1\Delta_u$ &5.83 &5.69 &5.61 &5.60 &5.60 &5.60 &5.60 &5.60 \\
$^3\Sigma_u^+$ &4.07 &4.06 &4.08 &4.10 &4.09 &4.10 &4.09 &4.11 \\
$^3\Delta_u$ &4.93 &4.86 &4.80 &4.80 &4.80 &4.80 &4.80 &4.80 \\
\hline
\end{tabular}
\end{small}
\end{table}
\clearpage
\subsection{Cyclopropenone, cyclopropenethione, and methylenecyclopropene}
\begin{table}[htp]
\caption{\small CC3 vertical transition energies of cyclopropenone, cyclopropenethione, and methylenecyclopropene using various atomic basis sets.
FC stands for frozen core. All values are in eV.}
\label{Table-S2}
\begin{small}
\begin{tabular}{l|ccccccc}
\hline
& {\Pop} & {\AVDZ} & {\AVTZ} & \multicolumn{2}{c}{\AVQZ} &{\DAVQZ} & {\AVFZ} \ \\
& FC & FC &FC & FC & Full & FC & FC \\
\hline
& \multicolumn{7}{c}{Cyclopropenone} \\
\hline
$^1B_1 (n \rightarrow \pi^\star)$ &4.32 &4.22 &4.21 &4.23 &4.22& 4.23 & 4.23\\
$^1A_2 (n \rightarrow \pi^\star)$ &5.68 &5.59 &5.57 &5.58 &5.57& 5.58 & 5.58\\
$^1B_2 (n \rightarrow 3s)$ &6.39 &6.21 &6.32 &6.37 &6.38& 6.36 & 6.38\\%
$^1B_2 (\pi \rightarrow \pi^\star)$ &6.70 &6.56 &6.54 &6.56 &6.56& 6.56 & 6.56\\
$^1B_2 (n \rightarrow 3p)$ &6.92 &6.88 &6.96 &6.99 &7.00& 6.96 & 6.99\\
$^1A_1 (n \rightarrow 3p)$ &7.00 &6.88 &7.00 &7.05 &7.06& 7.03 & 7.06\\
$^1A_1 (\pi \rightarrow \pi^\star)$ &8.51 &8.32 &8.28 &8.28 &8.28& 8.22 & 8.26\\
$^3B_1 (n \rightarrow \pi^\star)$ &4.02 &3.90 &3.91 &3.93 &3.92& 3.93 & 3.94\\
$^3B_2 (\pi \rightarrow \pi^\star)$ &4.92 &4.90 &4.89 &4.91 &4.90& 4.91 & 4.92\\
$^3A_2 (n \rightarrow \pi^\star)$ &5.48 &5.38 &5.37 &5.39 &5.37& 5.39 & 5.39\\
$^3A_1 (\pi \rightarrow \pi^\star)$ &6.89 &6.79 &6.83 &6.84 &6.83& 6.84 & 6.85\\
\hline
& \multicolumn{7}{c}{Cyclopropenethione} \\
\hline
$^1A_2 (n \rightarrow \pi^\star)$ &3.46 &3.47 &3.43 &3.44 &3.42& 3.44 & 3.43 \\
$^1B_1 (n \rightarrow \pi^\star)$ &3.45 &3.42 &3.43 &3.45 &3.43& 3.45 & 3.46\\
$^1B_2 (\pi \rightarrow \pi^\star)$ &4.67 &4.66 &4.64 &4.66 &4.64& 4.66 & 4.66 \\
$^1B_2 (n \rightarrow 3s)$ &5.26 &5.23 &5.34 &5.39 &5.39& 5.38 & 5.40 \\
$^1A_1 (\pi \rightarrow \pi^\star)$ &5.53 &5.52 &5.49 &5.49 &5.48& 5.49 & 5.49\\
$^1B_2 (n \rightarrow 3p)$ &5.83 &5.86 &5.93 &5.95 &5.95& 5.91 & 5.95 \\%$^a$, mais les autres aussi !!
$^3A_2 (n \rightarrow \pi^\star)$ &3.33 &3.34 &3.31 &3.31 &3.29& 3.31 & 3.31 \\
$^3B_1 (n \rightarrow \pi^\star)$ &3.34 &3.30 &3.31 &3.34 &3.32& 3.34 & 3.35\\
$^3B_2 (\pi \rightarrow \pi^\star)$ &4.01 &4.03 &4.02 &4.04 &4.03& 4.04 & 4.05 \\
$^3A_1 (\pi \rightarrow \pi^\star)$ &4.06 &4.09 &4.03 &4.04 &4.02& 4.04& 4.03 \\
\hline
& \multicolumn{7}{c}{Methylenecyclopropene} \\
\hline
$^1B_2 (\pi \rightarrow \pi^\star)$ &4.38 &4.32 &4.31 &4.31 &4.31& 4.31& 4.32 \\% 5Z: 4.32
$^1B_1 (\pi \rightarrow 3s)$ &5.65 &5.35 &5.44 &5.47 &5.48& 5.46& 5.47\\% 5Z: 5.47
$^1A_2 (\pi \rightarrow 3p)$ &5.97 &5.86 &5.95 &5.98 &5.99& 5.96& \hl{xxx}\\ %N122
$^1A_1 (\pi \rightarrow \pi^\star)$ &6.17 &6.15 &6.13 &6.09 &6.10& 5.98& 6.04\\%<= Stong mixing 5Z: 6.04 <= A italus<75> dans la liste des TBE ?
$^3B_2 (\pi \rightarrow \pi^\star)$ &3.50 &3.49 &3.50 &3.50 &3.50& 3.50& 3.50\\ %N122
$^3A_1 (\pi \rightarrow \pi^\star)$ &4.74 &4.74 &4.74 &4.75 &4.74& 4.74& 4.75\\% 5Z: 4.75
\hline
\end{tabular}
\begin{flushleft}
%$^a${Significant mixing.}
\end{flushleft}
\end{small}
\end{table}
\clearpage
\subsection{Acrolein, butadiene, and glyoxal}
\begin{sidewaystable}[htp]
\caption{\small CC3 vertical transition energies of acrolein, butadiene, and glyoxal using various atomic basis sets.
FC stands for frozen core. All values are in eV.}
\label{Table-S3}
\begin{small}
\begin{tabular}{l|ccccccc}
\hline
& {\Pop} & {\AVDZ} & {\AVTZ} & \multicolumn{2}{c}{\AVQZ} &{\DAVQZ} &{\AVFZ}\\
& FC & FC &FC & FC & Full & FC & FC \\
\hline
& \multicolumn{6}{c}{Acrolein} \\
\hline
$^1A'' (n \rightarrow \pi^\star)$ &3.83 &3.77 &3.74 &3.75 &3.74\\
$^1A' (\pi \rightarrow \pi^\star)$ &6.83 &6.67 &6.65 &6.65 &6.65\\
$^1A'' (n \rightarrow \pi^\star)$ &6.94 &6.75 &6.75 &6.77 &6.76\\
$^1A' (n \rightarrow 3s)$ &7.22 &6.99 &7.07 &7.11 &7.11\\
$^3A'' (n \rightarrow \pi^\star)$ &3.55 &3.47 &3.46 &3.47 &3.46\\
$^3A' (\pi \rightarrow \pi^\star)$ &3.94 &3.95 &3.94 &3.95 &3.94\\
$^3A' (\pi \rightarrow \pi^\star)$ &6.25 &6.22 &6.19 &6.20 &6.19\\
$^3A'' (n \rightarrow \pi^\star)$ &6.81 &6.60 &6.61 &6.63 &6.62\\
\hline
& \multicolumn{6}{c}{Butadiene} \\
\hline
$^1B_u (\pi \rightarrow \pi^\star)$ &6.41 &6.25 &6.22 &6.21 &6.22\\
$^1B_g (\pi \rightarrow 3s)$ &6.53 &6.26 &6.33 &6.35 &6.36\\
$^1A_g (\pi \rightarrow \pi^\star)$ &6.73 &6.68 &6.67 &6.67 &6.67& 6.67\\
$^1A_u (\pi \rightarrow 3p)$ &6.87 &6.57 &6.64 &6.66 &6.67\\
$^1A_u (\pi \rightarrow 3p)$ &6.93 &6.73 &6.80 &6.82 &6.83\\
$^1B_u (\pi \rightarrow 3p)$ &7.98 &7.86 &7.68 &7.54 &7.55\\
$^3B_u (\pi \rightarrow \pi^\star)$ &3.35 &3.36 &3.36 &3.37 &3.36\\
$^3A_g (\pi \rightarrow \pi^\star)$ &5.22 &5.21 &5.20 &5.21 &5.20\\
$^3B_g (\pi \rightarrow 3s)$ &6.46 &6.20 &6.28 &6.30 &6.31\\
\hline
& \multicolumn{6}{c}{Glyoxal} \\
\hline
$^1A_u (n \rightarrow \pi^\star)$ &2.94 &2.90 &2.88 &2.88 &2.87& 2.88& 2.88\\
$^1B_g (n \rightarrow \pi^\star)$ &4.34 &4.30 &4.27 &4.27 &4.27& 4.27& \\%~4.28
$^1A_g (n,n \rightarrow \pi^\star,\pi^\star)$&6.74 &6.70 &6.76 &6.76 &6.74& 6.76& 6.75 \\
$^1B_g (n \rightarrow \pi^\star)$ &6.81 &6.59 &6.58 &6.59 &6.58& 6.58& 6.59 \\
$^1B_u (n \rightarrow3p)$ &7.72 &7.55 &7.67 &7.72 &7.73& 7.72& 7.74\\
$^3A_u (n \rightarrow \pi^\star)$ &2.55 &2.49 &2.49 &2.49 &2.49& 2.49& 2.50\\
$^3B_g (n \rightarrow \pi^\star)$ &3.97 &3.91 &3.90 &3.91 &3.90& 3.91& \\
$^3B_u (\pi \rightarrow \pi^\star)$ &5.22 &5.20 &5.17 &5.18 &5.17& 5.18& 5.19\\
$^3A_g (\pi \rightarrow \pi^\star)$ &6.35 &6.34 &6.30 &6.31 &6.30& 6.31& 6.31\\
\hline
\end{tabular}
\end{small}
\end{sidewaystable}
\clearpage
\subsection{Acetone, cyanoformaldehyde, isobutene, propynal, thioacetone, and thiopropynal}
\begin{table}[htp]
\caption{\small CC3 vertical transition energies of acetone, cyanoformaldehyde, isobutene, propynal, thioacetone, and thiopropynal using various atomic basis sets.
FC stands for frozen core. All values are in eV.}
\label{Table-S4}
\begin{small}
\begin{tabular}{l|cccccc}
\hline
& {\Pop} & {\AVDZ} & {\AVTZ} & \multicolumn{2}{c}{\AVQZ} &{\DAVQZ} \\
& FC & FC &FC & FC & Full & FC\\
\hline
& \multicolumn{6}{c}{Acetone} \\
\hline
$^1A_2 (n \rightarrow \pi^\star)$ &4.55 &4.50 &4.48 &4.49 &4.48\\
$^1B_2 (n \rightarrow 3s)$ &6.65 &6.31 &6.43 &6.48 &6.49\\
$^1A_2 (n \rightarrow 3p)$ &7.83 &7.37 &7.45 &7.48 &7.49\\
$^1A_1 (n \rightarrow 3p)$ &7.81 &7.39 &7.48 &7.52 &7.53\\
$^1B_2 (n \rightarrow 3p)$ &7.87 &7.56 &7.59 &7.60 &7.61\\
$^3A_2 (n \rightarrow \pi^\star)$ &4.21 &4.16 &4.15 &4.17 &4.16\\
$^3A_1 (\pi \rightarrow \pi^\star)$ &6.32 &6.31 &6.28 &6.30 &6.28\\
\hline
& \multicolumn{6}{c}{Cyanoformaldehyde} \\
\hline
$^1A'' (n \rightarrow \pi^\star)$ &3.91 &3.86 &3.83 &3.84 &3.83 &3.84\\
$^1A'' (\pi \rightarrow \pi^\star)$ &6.64 &6.51 &6.42 &6.41 &6.41 &6.41\\
$^3A'' (n \rightarrow \pi^\star)$ &3.53 &3.47 &3.46 &3.47 &3.46 &3.47\\
$^3A' (\pi \rightarrow \pi^\star)$ &5.07 &5.03 &5.01 &5.02 &5.01 &5.02\\
\hline
& \multicolumn{6}{c}{Isobutene} \\
\hline
$^1B_1 (\pi \rightarrow 3s)$ &6.77 &6.39 &6.45 &6.47 &6.49\\
$^1A_1 (\pi \rightarrow 3p)$ &7.16 &7.00 &7.00 &6.99 &7.00\\
$^3A_1 (\pi \rightarrow \pi^\star)$ &4.52 &4.54 &4.53 &4.54 &4.54\\
\hline
& \multicolumn{6}{c}{Propynal} \\
\hline
$^1A'' (n \rightarrow \pi^\star)$ &3.90 &3.85 &3.82 &3.83 &3.82 &3.83\\
$^1A'' (\pi \rightarrow \pi^\star)$ &5.69 &5.59 &5.51 &5.50 &5.50 &5.50\\
$^3A'' (n \rightarrow \pi^\star)$ &3.56 &3.50 &3.49 &3.50 &3.49 &3.50\\
$^3A' (\pi \rightarrow \pi^\star)$ &4.46 &4.40 &4.43 &4.44 &4.43 &4.44\\
\hline
& \multicolumn{6}{c}{Thioacetone} \\
\hline
$^1A_2 (n \rightarrow \pi^\star)$ &2.58 &2.59 &2.55 &2.56 &\\
$^1B_2 (n \rightarrow 4s)$ &5.65 &5.44 &5.55 &5.60 &\\
$^1A_1 (\pi \rightarrow \pi^\star)$ &6.09 &5.97 &5.90 &5.88 &5.87\\
$^1B_2 (n \rightarrow 4p)$ &6.59 &6.45 &6.51 &6.52 &\\
$^1A_1 (n \rightarrow 4p)$ &6.95 &6.54 &6.61 &6.64 &6.64\\
$^3A_2 (n \rightarrow \pi^\star)$ &2.36 &2.36 &2.34 &2.35 &\\
$^3A_1 (\pi \rightarrow \pi^\star)$ &3.45 &3.51 &3.46 &3.47 &\\
\hline
& \multicolumn{5}{c}{Thiopropynal} \\
\hline
$^1A'' (n \rightarrow \pi^\star)$ &2.09 &2.09 &2.05 &2.06 &2.04\\
$^3A'' (n \rightarrow \pi^\star)$ &1.84 &1.83 &1.81 &1.82 &1.81\\
\hline
\end{tabular}
\end{small}
\end{table}
\clearpage
\subsection{Cyclopentadiene, furan, imidazole, pyrrole, and thiophene}
\begin{table}[htp]
\caption{\small CC3 vertical transition energies of furan and pyrrole using various atomic basis sets.
FC stands for frozen core. All values are in eV.}
\label{Table-S5}
\begin{small}
\begin{tabular}{l|ccccc}
\hline
& {\Pop} & {\AVDZ} & {\AVTZ} & \multicolumn{2}{c}{{\AVQZ}} \\
& FC & FC &FC & FC & Full \\
\hline
& \multicolumn{5}{c}{Furan} \\
\hline
$^1A_2 (\pi \rightarrow 3s)$ &6.26 &6.00 &6.08 &6.10 &6.12\\
$^1B_2 (\pi \rightarrow \pi^\star)$ &6.50 &6.37 &6.34 &6.34 &6.34\\
$^1A_1 (\pi \rightarrow \pi^\star)$ &6.71 &6.62 &6.58 &6.58 &6.58\\
$^1B_1 (\pi \rightarrow 3p)$ &6.76 &6.55 &6.63 &6.65 &6.67\\
$^1A_2 (\pi \rightarrow 3p)$ &6.97 &6.73 &6.80 &6.82 &6.83\\
$^1B_2 (\pi \rightarrow 3p)$ &7.53 &7.39 &7.23 &7.13 &7.14\\
$^3B_2 (\pi \rightarrow \pi^\star)$ &4.28 &4.25 &4.22 &4.22 &4.22\\
$^3A_1 (\pi \rightarrow \pi^\star)$ &5.56 &5.51 &5.48 &5.49 &5.48\\
$^3A_2 (\pi \rightarrow 3s)$ &6.18 &5.94 &6.02 &6.05 &6.07\\
$^3B_1 (\pi \rightarrow 3p)$ &6.69 &6.51 &6.59 &6.61 &6.63\\
\hline
& \multicolumn{5}{c}{Pyrrole} \\
\hline
$^1A_2 (\pi \rightarrow 3s)$ &5.25 &5.15 &5.24 &5.27 &\hl{XXX} \\
$^1B_1 (\pi \rightarrow 3p)$ &5.99 &5.89 &5.98 &6.01 &6.02 \\
$^1A_2 (\pi \rightarrow 3p)$ &6.27 &5.94 &6.01 &6.03 &\hl{XXX} \\
$^1B_2 (\pi \rightarrow \pi^\star)$ &6.33 &6.28 &6.25 &6.22 &6.23 \\
$^1A_1 (\pi \rightarrow \pi^\star)$ &6.43 &6.35 &6.32 &6.31 &6.31 \\
$^1B_2 (\pi \rightarrow 3p)$ &7.20 &7.00 &6.83 &6.74 &6.75 \\
$^3B_2 (\pi \rightarrow \pi^\star)$ &4.59 &4.56 &4.53 &4.53 &4.52 \\
$^3A_2 (\pi \rightarrow 3s)$ &5.22 &5.12 &5.21 &5.24 &\hl{XXX} \\
$^3A_1 (\pi \rightarrow \pi^\star)$ &5.54 &5.49 &5.46 &5.47 &5.46 \\
$^3B_1 (\pi \rightarrow 3p)$ &5.91 &5.82 &5.92 &5.95 &5.97 \\
\hline
\end{tabular}
\end{small}
\end{table}
\begin{table}[htp]
\caption{\small CC3 vertical transition energies of cyclopentadiene, imidazole, and thiophene using various atomic basis sets.
FC stands for frozen core. All values are in eV.}
\label{Table-S6}
\begin{small}
\begin{tabular}{l|cccc}
\hline
& {\Pop} & {\AVDZ} & {\AVTZ} & {{\AVQZ}} \\
& FC & FC &FC & FC \\
\hline
& \multicolumn{4}{c}{Cyclopentadiene} \\
\hline
$^1B_2 (\pi \rightarrow \pi^\star)$ &5.79 &5.59 &5.54 &5.53 \\
$^1A_2 (\pi \rightarrow 3s)$ &6.08 &5.70 &5.77 &5.79 \\
$^1B_1 (\pi \rightarrow 3p)$ &6.57 &6.34 &6.40 &6.42 \\
$^1A_2 (\pi \rightarrow 3p)$ &6.67 &6.39 &6.45 &6.46 \\
$^1B_2 (\pi \rightarrow 3p)$ &7.06 &6.55 &6.56 &6.55 \\
$^1A_1 (\pi \rightarrow \pi^\star)$ &6.67 &6.59 &6.57 &6.57 \\
$^3B_2 (\pi \rightarrow \pi^\star)$ &3.33 &3.32 &3.32 &3.32 \\
$^3A_1 (\pi \rightarrow \pi^\star)$ &5.16 &5.14 &5.12 &5.13 \\
$^3A_2 (\pi \rightarrow 3s)$ &6.01 &5.65 &5.73 &5.75 \\
$^3B_1 (\pi \rightarrow 3p)$ &6.51 &6.30 &6.36 &6.38 \\
\hline
& \multicolumn{4}{c}{Imidazole} \\
\hline
$^1A'' (\pi \rightarrow 3s)$ &5.77 &5.60 &5.71 &5.73 \\
$^1A' (\pi \rightarrow \pi^\star)$ &6.51 &6.43 &6.41 &6.41 \\
$^1A'' (n \rightarrow \pi^\star)$ &6.66 &6.42 &6.50 &6.53 \\
$^1A' (\pi \rightarrow 3p)$ &7.04 &6.93 &6.87 &6.86 \\
$^3A' (\pi \rightarrow \pi^\star)$ &4.83 &4.78 &4.75 &4.76 \\
$^3A'' (\pi \rightarrow 3s)$ &5.72 &5.57 &5.67 &5.70 \\
$^3A' (\pi \rightarrow \pi^\star)$ &5.88 &5.78 &5.74 &5.75 \\
$^3A'' (n \rightarrow \pi^\star)$ &6.48 &6.37 &6.33 &6.33 \\
\hline
& \multicolumn{4}{c}{Thiophene} \\
\hline
$^1A_1 (\pi \rightarrow \pi^\star)$ &5.79 &5.70 &5.65 &5.64\\
$^1B_2 (\pi \rightarrow \pi^\star)$ &6.23 &6.05 &5.96 &5.94\\
$^1A_2 (\pi \rightarrow 3s)$ &6.26 &6.07 &6.14 &6.16\\
$^1B_1 (\pi \rightarrow 3p)$ &6.18 &6.19 &6.14 &6.11\\
$^1A_2 (\pi \rightarrow 3p)$ &6.32 &6.33 &6.25 &6.22\\
$^1B_1 (\pi \rightarrow 3s)$ &6.62 &6.42 &6.50 &6.53\\
$^1B_2 (\pi \rightarrow 3p)$ &7.45 &7.45 &7.29 &7.18\\
$^1A_1 (\pi \rightarrow \pi^\star)$ &7.50 &7.41 &7.35 &7.33\\
$^3B_2 (\pi \rightarrow \pi^\star)$ &3.95 &3.96 &3.94 &3.93\\
$^3A_1 (\pi \rightarrow \pi^\star)$ &4.90 &4.82 &4.77 &4.77\\
$^3B_1 (\pi \rightarrow 3p)$ &6.00 &6.01 &5.95 &5.92\\
$^3A_2 (\pi \rightarrow 3s)$ &6.20 &6.01 &6.09 &5.99\\
\hline
\end{tabular}
\end{small}
\end{table}
\clearpage
\subsection{Benzene, pyrazine, and tetrazine}
\begin{table}[htp]
\caption{\small CC3 vertical transition energies of benzene using various atomic basis sets.
FC stands for frozen core. All values are in eV.}
\label{Table-S7}
\begin{small}
\begin{tabular}{l|cccc}
\hline
& {\Pop} & {\AVDZ} & {\AVTZ} & {\AVQZ} \\
& FC & FC &FC & FC \\
\hline
& \multicolumn{4}{c}{Benzene} \\
\hline
$^1B_{2u} (\pi \rightarrow \pi^\star)$ &5.13 &5.11 &5.09 &5.09\\
$^1B_{1u} (\pi \rightarrow \pi^\star)$ &6.68 &6.50 &6.44 &6.43\\
$^1E_{1g} (\pi \rightarrow 3s)$ &6.75 &6.46 &6.52 &6.54\\
$^1A_{2u} (\pi \rightarrow 3p)$ &7.24 &7.02 &7.08 &7.10\\
$^1E_{2u} (\pi \rightarrow 3p)$ &7.34 &7.09 &7.15 &7.16\\
$^3B_{1u} (\pi \rightarrow \pi^\star)$ &4.18 &4.19 &4.18 &4.19\\
$^3E_{1u}(\pi \rightarrow \pi^\star)$ &4.95 &4.89 &4.86 &4.87\\
$^3B_{2u} (\pi \rightarrow \pi^\star)$ &6.06 &5.86 &5.81 &5.81\\
\hline
\end{tabular}
\end{small}
\end{table}
\clearpage
\begin{table}[htp]
\caption{\small CC3 vertical transition energies of pyrazine and tetrazine using various atomic basis sets.
FC stands for frozen core. All values are in eV.}
\label{Table-S8}
\begin{small}
\begin{tabular}{l|ccccc}
\hline
& {\Pop} & {\AVDZ} & {\AVTZ} & \multicolumn{2}{c}{{\AVQZ}} \\
& FC & FC &FC & FC & Full \\
\hline
& \multicolumn{5}{c}{Pyrazine} \\
\hline
$^1B_{3u} (n \rightarrow \pi^\star)$ & 4.28 &4.19 &4.14 &4.14\\
$^1A_{u} (n \rightarrow \pi^\star)$ & 5.08 &4.98 &4.97 &4.98\\
$^1B_{2u} (\pi \rightarrow \pi^\star)$ & 5.10 &5.07 &5.03 &5.02\\
$^1B_{2g} (n \rightarrow \pi^\star)$ & 5.86 &5.78 &5.71 &5.71\\
$^1A_{g} (n \rightarrow 3s)$ & 6.74 &6.54 &6.66 &6.70& 6.71\\
$^1B_{1g} (n \rightarrow \pi^\star)$ & 6.87 &6.75 &6.73 &6.73\\
$^1B_{1u} (\pi \rightarrow \pi^\star)$ & 7.10 &6.92 &6.86 &6.85& 6.85\\
$^1B_{1g} (\pi \rightarrow 3s)$ & 7.36 &7.13 &7.20 &7.23\\
$^1B_{2u} (n \rightarrow 3p)$ & 7.39 &7.14 &7.25 &7.29\\
$^1B_{1u} (n \rightarrow 3p)$ & 7.56 &7.38 &7.45 &7.48& 7.49\\
$^1B_{1u} (\pi \rightarrow \pi^\star)$ & 8.19 &7.99 &7.94 &7.93& 7.93\\
$^3B_{3u} (n \rightarrow \pi^\star)$ & 3.68 &3.60 &3.59 &3.59\\
$^3B_{1u} (\pi \rightarrow \pi^\star)$ & 4.39 &4.40 &4.39 &4.40& 4.39\\
$^3B_{2u} (\pi \rightarrow \pi^\star)$ & 4.56 &4.46 &4.40 &4.40\\
$^3A_{u} (n \rightarrow \pi^\star)$ & 5.05 &4.93 &4.93 &4.94\\
$^3B_{2g} (n \rightarrow \pi^\star)$ & 5.18 &5.11 &5.08 &5.09\\
$^3B_{1u} (\pi \rightarrow \pi^\star)$ & 5.38 &5.32 &5.29 &5.29& 5.28\\
\hline
& \multicolumn{5}{c}{Tetrazine} \\
\hline
$^1B_{3u} (n \rightarrow \pi^\star)$ & 2.53 &2.49 &2.46 &2.45 &2.45\\
$^1A_{u} (n \rightarrow \pi^\star)$ & 3.75 &3.69 &3.67 &3.68 &3.67\\
$^1A_{g} (n,n \rightarrow \pi^\star, \pi^\star)$ & 6.22 &6.22 &6.21 &6.19 &6.17\\
$^1B_{1g} (n \rightarrow \pi^\star)$ & 5.01 &4.97 &4.91 &4.90 &4.88\\
$^1B_{2u} (\pi \rightarrow \pi^\star)$ & 5.29 &5.27 &5.23 &5.22 &5.21\\
$^1B_{2g} (n \rightarrow \pi^\star)$ & 5.56 &5.53 &5.46 &5.46 &5.45\\
$^1A_{u} (n \rightarrow \pi^\star)$ & 5.61 &5.59 &5.52 &5.52 &5.50\\
$^1B_{3g} (n,n \rightarrow \pi^\star, \pi^\star)$ & 7.64 &7.62 &7.62 &7.60 &7.58\\
$^1B_{2g} (n \rightarrow \pi^\star)$ & 6.24 &6.17 &6.13 &6.13 &6.10\\
$^1B_{1g} (n \rightarrow \pi^\star)$ & 7.04 &6.98 &6.92 &6.92 &6.91\\
$^3B_{3u} (n \rightarrow \pi^\star)$ & 1.87 &1.86 &1.85 &1.86 &1.85\\
$^3A_{u} (n \rightarrow \pi^\star)$ & 3.48 &3.43 &3.44 &3.45 &3.43\\
$^3B_{1g} (n \rightarrow \pi^\star)$ & 4.25 &4.23 &4.20 &4.21 &4.18\\
$^3B_{1u} (\pi \rightarrow \pi^\star)$ & 4.54 &4.54 &4.54 &4.54 &4.53\\
$^3B_{2u} (\pi \rightarrow \pi^\star)$ & 4.65 &4.58 &4.52 &4.52 &4.51\\
$^3B_{2g} (n \rightarrow \pi^\star)$ & 5.11 &5.09 &5.05 &5.05 &5.04\\
$^3A_{u} (n \rightarrow \pi^\star)$ & 5.17 &5.15 &5.11 &5.11 &5.10\\
$^3B_{3g} (n,n \rightarrow \pi^\star, \pi^\star)$ & 7.35 &7.33 &7.35 &7.34 &7.32\\
$^3B_{1u} (\pi \rightarrow \pi^\star)$ & 5.51 &5.46 &5.42 &5.43 &5.42\\
\hline
\end{tabular}
\end{small}
\end{table}
\clearpage
\subsubsection{Pyridazine, pyridine, pyrimidine and triazine}
\begin{table}[htp]
\caption{\small CC3 vertical transition energies of pyridazine and pyridine using various atomic basis sets.
FC stands for frozen core. All values are in eV.}
\label{Table-S9}
\begin{small}
\begin{tabular}{l|cccc}
\hline
& {\Pop} & {\AVDZ} & {\AVTZ} & {\AVQZ} \\
& FC & FC &FC & FC \\
\hline
& \multicolumn{4}{c}{Pyridazine} \\
\hline
$^1B_1 (n \rightarrow \pi^\star)$ &3.95 &3.86 &3.83 &\\
$^1A_2 (n \rightarrow \pi^\star)$ &4.49 &4.39 &4.37 &\\
$^1A_1 (\pi \rightarrow \pi^\star)$ &5.36 &5.33 &5.29 &5.29\\
$^1A_2 (n \rightarrow \pi^\star)$ &5.88 &5.80 &5.74 &5.74\\
$^1B_2 (n \rightarrow 3s)$ &6.26 &6.06 &6.17 &\\
$^1B_1 (n \rightarrow \pi^\star)$ &6.51 &6.41 &6.37 &\\
$^1B_2 (\pi \rightarrow \pi^\star)$ &6.96 &6.79 &6.74 &\\
$^3B_1 (n \rightarrow \pi^\star)$ &3.27 &3.20 &3.19 &3.20\\
$^3A_2 (n \rightarrow \pi^\star)$ &4.19 &4.11 &4.11 &4.12\\
$^3B_2 (\pi \rightarrow \pi^\star)$ &4.39 &4.39 &4.38 &4.39\\
$^3A_1 (\pi \rightarrow \pi^\star)$ &4.93 &4.87 &4.83 &4.82\\
\hline
& \multicolumn{4}{c}{Pyridine} \\
\hline
$^1B_1 (n \rightarrow \pi^\star)$ &5.12 &5.01 &4.96\\
$^1B_2 (\pi \rightarrow \pi^\star)$ &5.23 &5.21 &5.17\\
$^1A_2 (n \rightarrow \pi^\star)$ &5.55 &5.41 &5.40\\
$^1A_1 (\pi \rightarrow \pi^\star)$ &6.84 &6.64 &6.63\\
$^1A_1 (n \rightarrow 3s)$ &6.92 &6.71 &6.76\\
$^1A_2 (\pi \rightarrow 3s)$ &6.98 &6.74 &6.81& 6.83\\
$^1B_2 (\pi \rightarrow \pi^\star)$ &7.50 &7.40 &7.38\\
$^1B_1 (\pi \rightarrow 3p)$ &7.54 &7.32 &7.38\\
$^1A_1 (\pi \rightarrow \pi^\star)$ &7.56 &7.34 &7.39\\
$^3A_1 (\pi \rightarrow \pi^\star)$ &4.33 &4.34 &4.33& 4.34\\
$^3B_1 (n \rightarrow \pi^\star)$ &4.57 &4.47 &4.46& 4.47\\
$^3B_2 (\pi \rightarrow \pi^\star)$ &4.92 &4.83 &4.79& 4.79\\
$^3A_1 (\pi \rightarrow \pi^\star)$ &5.14 &5.08 &5.05& 5.05\\
$^3A_2 (n \rightarrow \pi^\star)$ &5.51 &5.37 &5.35& 5.37\\
$^3B_2 (\pi \rightarrow \pi^\star)$ &6.46 &6.30 &6.25& 6.25\\
\hline
\end{tabular}
\end{small}
\end{table}
\clearpage
\begin{table}[htp]
\caption{\small CC3 vertical transition energies of pyrimidine and triazine using various atomic basis sets.
FC stands for frozen core. All values are in eV.}
\label{Table-S10}
\begin{small}
\begin{tabular}{l|cccc}
\hline
& {\Pop} & {\AVDZ} & {\AVTZ} & {\AVQZ} \\
& FC & FC &FC & FC \\
\hline
& \multicolumn{4}{c}{Pyrimidine} \\
\hline
$^1B_1 (n \rightarrow \pi^\star)$ & 4.58 &4.48 &4.44 &4.45\\
$^1A_2 (n \rightarrow \pi^\star)$ & 4.99 &4.89 &4.86 &4.87\\
$^1B_2 (\pi \rightarrow \pi^\star)$ & 5.47 &5.44 &5.41 &5.40\\
$^1A_2 (n \rightarrow \pi^\star)$ & 6.07 &5.98 &5.93 &5.93\\
$^1B_1 (n \rightarrow \pi^\star)$ & 6.39 &6.29 &6.26 &6.27\\
$^1B_2 (n \rightarrow 3s)$ & 6.81 &6.61 &6.72 &6.76\\
$^1A_1 (\pi \rightarrow \pi^\star)$ & 7.08 &6.93 &6.87 &6.86\\
$^3B_1 (n \rightarrow \pi^\star)$ & 4.20 &4.12 &4.10 &4.11\\
$^3A_1 (\pi \rightarrow \pi^\star)$ & 4.55 &4.56 &4.55 &4.56\\
$^3A_2 (n \rightarrow \pi^\star)$ & 4.77 &4.67 &4.66 &4.67\\
$^3B_2 (\pi \rightarrow \pi^\star)$ & 5.08 &5.00 &4.96 &4.96\\
\hline
& \multicolumn{4}{c}{Triazine} \\
\hline
$^1A_1'' (n \rightarrow \pi^\star)$ & 4.85 &4.76 &4.73 &4.74\\
$^1A_2'' (n \rightarrow \pi^\star)$ & 4.84 &4.78 &4.74 &4.74\\
$^1E'' (n \rightarrow \pi^\star)$ & 4.89 &4.82 &4.78 &4.79\\
$^1A_2' (\pi \rightarrow \pi^\star)$ & 5.84 &5.81 &5.78 &5.78\\
$^1A_1' (\pi \rightarrow \pi^\star)$ & 7.45 &7.31 &7.24 &7.23\\
$^1E' (n \rightarrow 3s)$ & 7.44 &7.24 &7.35 &7.39\\
$^1E'' (n \rightarrow \pi^\star)$ & 7.89 &7.82 &7.79 &7.78\\
$^1E' (\pi \rightarrow \pi^\star)$ & 8.12 &7.97 &7.92 &7.92\\
$^3A_2'' (n \rightarrow \pi^\star)$ & 4.40 &4.35 &4.33 &4.34\\
$^3E'' (n \rightarrow \pi^\star)$ & 4.59 &4.52 &4.51 &4.51\\
$^3A_1'' (n \rightarrow \pi^\star)$ & 4.87 &4.78 &4.75 &4.76\\
$^3A_1' (\pi \rightarrow \pi^\star)$ & 4.88 &4.88 &4.88 &4.89\\
$^3E' (\pi \rightarrow \pi^\star)$ & 5.70 &5.64 &5.61 &5.61\\
$^3A_2' (\pi \rightarrow \pi^\star)$ & 6.85 &6.69 &6.63 &6.62\\
\hline
\end{tabular}
\end{small}
\end{table}
\clearpage
\clearpage
\section{Multiconfigurational results}
\subsection{Basis set effects}
\begin{table}[htp]
\caption{\small Vertical transition energies of cyanoacetylene, cyanogen, and diacetylene using various atomic basis sets and
multi-reference methods. All values are in eV and have been obtained within the FC approximation. The CASPT2 calculations
are performed with a level shift of 0.3 and a IPEA of 0.25. Pop, AVDZ, AVTZ, and AVQZ respectively stand for {\Pop}, {\AVDZ},
{\AVTZ}, and {\AVQZ}. }
\label{Table-S1b}
\begin{footnotesize}
\begin{tabular}{l|cccccccccccc}
\hline
& \multicolumn{4}{c}{CASPT2(8,8)} & \multicolumn{4}{c}{PC-NEVPT2(8,8)} & \multicolumn{4}{c}{SC-NEVPT2(8,8)} \\
& Pop &AVDZ & AVTZ & AVQZ & Pop &AVDZ & AVTZ & AVQZ& Pop &AVDZ & AVTZ & AVQZ \\
\hline
& \multicolumn{12}{c}{Cyanoacetylene} \\
\hline
$^1\Sigma^-$ & & 6.00 & 5.86 & & & 5.93 & 5.78 & & & 5.98 & 5.83 & \\
$^1\Delta$ & & 6.26 & 6.13 & & & 6.22 & 6.10 & & & 6.27 & 6.14 & \\
$^3\Sigma^+$ & & 4.47 & 4.45 & & & 4.46 & 4.45 & & & 4.51 & 4.49 & \\
$^3\Delta$ & & 5.30 & 5.21 & & & 5.28 & 5.19 & & & 5.31 & 5.23 & \\
\hline
& \multicolumn{12}{c}{Cyanogen} \\
\hline
$^1\Sigma_u^-$ & 6.63 & 6.56 & 6.40 & 6.37 & 6.56 & 6.49 & 6.32 & 6.29 & 6.61 & 6.54 & 6.37 & 6.34 \\
$^1\Delta_u$ & 6.93 & 6.84 & 6.70 & 6.66 & 6.91 & 6.81 & 6.66 & 6.63 & 6.95 & 6.86 & 6.71 & 6.68 \\
$^3\Sigma_u^+$ & 4.91 & 4.89 & 4.86 & 4.86 & 4.92 & 4.91 & 4.88 & 4.89 & 4.96 & 4.95 & 4.92 & 4.93 \\
$^1\Sigma_u^-$[F] & & 5.23 & 5.07 & & & 5.14 & 4.97 & & & 5.17 & 5.01 & \\
\hline
& \multicolumn{12}{c}{Diacetylene} \\
\hline
$^1\Sigma_u^-$ & & 5.56 & 5.43 & & & 5.47 & 5.33 & & & 5.53 & 5.39 & \\
$^1\Delta_u$ & & 5.80 & 5.68 & & & 5.73 & 5.61 & & & 5.78 & 5.67 & \\
$^3\Sigma_u^+$ & & 4.12 & 4.11 & & & 4.09 & 4.08 & & & 4.14 & 4.13 & \\
$^3\Delta_u$ & & 4.89 & 4.81 & & & 4.86 & 4.78 & & & 4.90 & 4.82 & \\
\hline
\end{tabular}
\end{footnotesize}
\end{table}
\clearpage
\subsection{Active Spaces}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of acetone.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Acetone &$^1A_2 (\Val; n \ra \pis)$ &4.57$^a$,4.48$^b$ \\
&$^1B_2 (\Ryd; n \ra 3s)$ &6.81$^c$ \\
&$^1A_2 (\Ryd; n \ra 3p)$ &7.65$^b$ \\
&$^1A_1 (\Ryd; n \ra 3p)$ &7.75$^d$ \\
&$^1B_2 (\Ryd; n \ra 3p)$ &7.91$^c$ \\
&$^3A_2 (\Val; n \ra \pis)$ &4.20$^a$ \\
&$^3A_1 (\Val; \pi \ra \pis)$ &6.28$^e$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (6e,5o) active space including valence $\pi$, $n_\text{O}$, $\si_\text{CO}$ and $\si^*_\text{CO}$ orbitals.
$^b$Using reference (6e,6o) active space including valence $\pi$, $n_\text{O}$, $\si_\text{CO}$, $\si^*_\text{CO}$ and $3p_x$ orbitals.
$^c$Using reference (6e,7o) active space including valence $\pi$, $n_\text{O}$, $\si_\text{CO}$, $\si^*_\text{CO}$, 3s and $3p_z$ orbitals.
$^d$Using reference (6e,6o) active space including valence $\pi$, $n_\text{O}$, $\si_\text{CO}$, $\si^*_\text{CO}$ and $3p_y$ orbitals.
$^e$Using reference (4e,4o) active space including valence $\pi$, $\si_\text{CO}$ and $\si^*_\text{CO}$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of acrolein.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Acrolein &$^1A'' (\Val; n \ra \pis)$ &3.76$^a$,3.73$^b$ \\
&$^1A' (\Val; \pi \ra \pis)$ &6.67$^a$ \\
&$^1A'' (\Val; n \ra \pis)$ &7.16$^{a,c}$,7.57$^{b,c}$ \\
&$^1A' (\Ryd; n \ra 3s)$ &7.05$^a$ \\
&$^3A'' (\Val; n \ra \pis)$ &3.46$^a$,3.44$^b$ \\
&$^3A' (\Val; \pi \ra \pis)$ &3.95$^a$ \\
&$^3A' (\Val; \pi \ra \pis)$ &6.23$^a$ \\
&$^3A'' (\Val; n \ra \pis)$ &6.83$^{a,d}$,7.06$^{b,d}$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (12e,12o) active space including valence $\pi$, $\si_\text{CC}$, $\si_\text{CO}$, $\si^*_\text{CC}$, $\si^*_\text{CO}$, $n_\text{O}$ and 3s orbitals.
$^b$Using reference (12e,13o) active space including valence $\pi$, $\si_\text{CC}$, $\si_\text{CO}$, $\si^*_\text{CC}$, $\si^*_\text{CO}$, $n_\text{O}$, 3s and $3p_z$ orbitals.
$^c$Substantial Rydberg and doubly-excited character.
$^d$Substantial doubly-excited character.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of benzene.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Benzene &$^1B_{2u} (\Val; \pi \ra \pis)$ &5.32$^a$,5.32$^b$ \\
&$^1B_{1u} (\Val; \pi \ra \pis)$ &6.01$^a$,6.43$^b$ \\
&$^1E_{1g} (\Ryd; \pi \ra 3s)$ &6.75$^c$ \\
&$^1A_{2u} (\Ryd; \pi \ra 3p)$ &7.40$^d$\\
&$^1E_{2u} (\Ryd; \pi \ra 3p)$ &7.45$^d$ \\
&$^3B_{1u} (\Val; \pi \ra \pis)$ &4.44$^a$,4.32$^b$\\
&$^3E_{1u}(\Val; \pi \ra \pis)$ &4.99$^a$,4.92$^b$\\
&$^3B_{2u} (\Val; \pi \ra \pis)$ &5.30$^a$,5.51$^b$\\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (6e,6o) active space including valence $\pi$ orbitals.
$^b$Using reference (6e,9o) active space including valence $\pi$ and three $3p_z$ orbitals.
$^c$Using reference (6e,7o) active space including valence $\pi$ and 3s orbitals.
$^d$Using reference (6e,8o) active space including valence $\pi$, $3p_x$ and $3p_y$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of butadiene.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Butadiene &$^1B_u (\Val; \pi \ra \pis)$ &6.04$^a$,6.73$^b$,6.68$^c$ \\
&$^1B_g (\Ryd; \pi \ra 3s)$ &6.44$^d$ \\
&$^1A_g (\Val; \pi \ra \pis)$ &6.70$^a$ \\
&$^1A_u (\Ryd; \pi \ra 3p)$ &6.84$^e$ \\
&$^1A_u (\Ryd; \pi \ra 3p)$ &7.01$^e$ \\
&$^1B_u (\Ryd; \pi \ra 3p)$ &6.99$^b$,7.45$^c$ \\
&$^3B_u (\Val; \pi \ra \pis)$ &3.40$^a$ \\
&$^3A_g (\Val; \pi \ra \pis)$ &5.30$^a$ \\
&$^3B_g (\Ryd; \pi \ra 3s)$ &6.38$^d$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (10e,10o) active space including valence $\pi$, $\si_\text{CC}$ and $\si^*_\text{CC}$ orbitals.
$^b$Using reference (10e,11o) active space including valence $\pi$, $\si_\text{CC}$, $\si^*_\text{CC}$ and $3p_z$ orbitals.
$^c$Using reference (4e,8o) active space including valence $\pi$ and four $3p_z$.
$^d$Using reference (10e,11o) active space including valence $\pi$, $\si_\text{CC}$, $\si^*_\text{CC}$ and 3s orbitals.
$^e$Using reference (10e,12o) active space including valence $\pi$, $\si_\text{CC}$, $\si^*_\text{CC}$, $3p_x$ and $3p_y$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of cyanoacetylene.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2$^a$ \\
\hline
Cyanoacetylene &$^1\Sigma^- (\Val; \pi \ra \pis)$ & 5.78 \\
&$^1\Delta (\Val; \pi \ra \pis)$ & 6.10 \\
&$^3\Sigma^+ (\Val; \pi \ra \pis)$ & 4.45 \\
&$^3\Delta (\Val; \pi \ra \pis)$ & 5.19 \\
&$^1A'' [\mathrm{F}] (\Val; \pi \ra \pis)$ & 3.50 \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$All calculations using a full valence $\pi$ active space of (8e,8o).
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of cyanoformaldehyde.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Cyanoformaldehyde &$^1A'' (\Val; n \ra \pis)$ &3.98$^a$ \\
&$^1A'' (\Val; \pi \ra \pis)$ & 6.44$^a$ \\
&$^3A'' (\Val; n \ra \pis)$ & 3.58$^a$ \\
&$^3A' (\Val; \pi \ra \pis)$ & 5.35$^b$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$ Using reference (8e,7o) active space including valence $\pi$ and $n_\text{O}$ orbitals.
$^b$ Using reference (6e,6o) active space including valence $\pi$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of cyanogen.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2$^a$ \\
\hline
Cyanogen & $^1\Sigma_u^- (\Val; \pi \ra \pis)$ & 6.32 \\
& $^1\Delta_u (\Val; \pi \ra \pis)$ & 6.66 \\
& $^3\Sigma_u^+ (\Val; \pi \ra \pis)$ & 4.88 \\
& $^1\Sigma_u^- [\mathrm{F}] (\Val; \pi \ra \pis)$ & 4.97 \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$All calculations using a full valence $\pi$ active space of (8e,8o).
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of cyclopentadiene.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Cyclopentadiene &$^1B_2 (\Val; \pi \ra \pis)$ &4.96$^a$,4.92$^b$,5.65$^c$ \\
&$^1A_2 (\Ryd; \pi \ra 3s)$ &5.92$^d$ \\
&$^1B_1 (\Ryd; \pi \ra 3p)$ &6.42$^e$ \\
&$^1A_2 (\Ryd; \pi \ra 3p)$ &6.59$^d$ \\
&$^1B_2 (\Ryd; \pi \ra 3p)$ &6.58$^b$,6.60$^c$ \\
&$^1A_1 (\Val; \pi \ra \pis)$ &6.75$^{a,f}$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ &3.41$^a$ \\
&$^3A_1 (\Val; \pi \ra \pis)$ &5.30$^a$ \\
&$^3A_2 (\Ryd; \pi \ra 3s)$ &5.73$^g$ \\
&$^3B_1 (\Ryd; \pi \ra 3p)$ &6.40$^e$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (4e,4o) active space including valence $\pi$ orbitals.
$^b$Using reference (4e,5o) active space including valence $\pi$ and $3p_x$ orbitals.
$^c$Using reference (4e,8o) active space including valence $\pi$ and four $3p_x$ orbitals.
$^d$Using reference (4e,6o) active space including valence $\pi$, 3s and $3p_z$ orbitals.
$^e$Using reference (4e,5o) active space including valence $\pi$ and $3p_y$ orbitals.
$^f$Strong double-excitation character.
$^g$Using reference (4e,5o) active space including valence $\pi$ and 3s orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of cyclopropenone.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2$^a$ \\
\hline
Cyclopropenone &$^1B_1 (\Val; n \ra \pis)$ & 4.04 \\
&$^1A_2 (\Val; n \ra \pis)$ & 5.85 \\
&$^1B_2 (\Ryd; n \ra 3s)$ & 6.51 \\
&$^1B_2 (\Val; \pi \ra \pis$) & 6.82 \\
&$^1B_2 (\Ryd; n \ra 3p)$ & 7.07 \\
&$^1A_1 (\Ryd; n \ra 3p)$ & 7.28 \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 8.19 \\
&$^3B_1 (\Val; n \ra \pis)$ & 3.51 \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 5.10 \\
&$^3A_2 (\Val; n \ra \pis)$ & 5.60 \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 7.16 \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$All calculation using reference (6e,7o) active space averaging with the ground state for each irreducible representation.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of cyclopropenethione.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Cyclopropenethione &$^1A_2 (\Val; n \ra \pis)$ &3.52$^a$ \\
&$^1B_1 (\Val; n \ra \pis)$ &3.50$^a$ \\
&$^1B_2 (\Val; \pi \ra \pis)$ &4.77$^b$ \\
&$^1B_2 (\Ryd; n \ra 3s)$ &5.35$^b$ \\
&$^1A_1 (\Val; \pi \ra \pis)$ &5.54$^c$ \\
&$^1B_2 (\Ryd; n \ra 3p)$ &5.99$^b$ \\
&$^3A_2 (\Val; n \ra \pis)$ &3.38$^a$ \\
&$^3B_1 (\Val; n \ra \pis)$ &3.40$^a$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ &4.21$^c$,4.17$^b$ \\
&$^3A_1 (\Val; \pi \ra \pis)$ &4.13$^c$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (6e,5o) active space.
$^b$Using reference (6e,7o) active space.
$^c$Using reference (4e,4o) active space.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of diacetylene.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2$^a$ \\
\hline
Diacetylene &$^1\Sigma_u^- (\Val; \pi \ra \pis)$ & 5.33 \\
&$^1\Delta_u (\Val; \pi \ra \pis)$ & 5.61 \\
&$^3\Sigma_u^+ (\Val; \pi \ra \pis)$ & 4.08 \\
&$^3\Delta_u (\Val; \pi \ra \pis)$ & 4.78 \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$All calculations using a full valence $\pi$ active space of (8e,8o).
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of furan.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Furan &$^1A_2 (\Ryd; \pi \ra 3s)$ & 6.28$^a$ \\
&$^1B_2 (\Val; \pi \ra \pis)$ & 5.92$^b$,6.20$^{c,d}$ \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 6.77$^{b,e}$ \\
&$^1B_1 (\Ryd; \pi \ra 3p)$ & 6.71$^f$ \\
&$^1A_2 (\Ryd; \pi \ra 3p)$ & 6.99$^a$ \\
&$^1B_2 (\Ryd; \pi \ra 3p)$ & 7.01$^{c,d}$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 4.42$^b$ \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 5.60$^b$ \\
&$^3A_2 (\Ryd; \pi \ra 3s)$ & 6.08$^g$ \\
&$^3B_1 (\Ryd; \pi \ra 3p)$ & 6.68$^f$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (6e,7o) active space including valence $\pi$, 3s and $3p_z$ orbitals.
$^b$Using reference (6e,5o) active space including valence $\pi$ orbitals.
$^c$Using reference (6e,6o) active space including valence $\pi$ and $3p_x$ orbitals.
$^d$Increasing the $\pi$ $3p_x$ active space leads to strong mixing in the zeroth-order wavefunction requiring QD-NEVPT2 (see Pastore et al., Chem. Phys. Lett. 2006, 426, 445--451).
$^e$Strong double-excitation character.
$^f$Using reference (6e,6o) active space including valence $\pi$ and $3p_y$ orbitals.
$^g$Using reference (4e,5o) active space including valence $\pi$ and 3s orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of glyoxal.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Glyoxal &$^1A_u (\Val; n \ra \pis)$ & 2.90$^a$ \\
&$^1B_g (\Val; n \ra \pis)$ & 4.31$^a$,4.30$^b$ \\
&$^1A_g (\Val; n,n \ra \pis,\pis)$ & 5.52$^a$ \\
&$^1B_g (\Val; n \ra \pis)$ & 6.91$^{a,c}$,6.64$^{b,c}$ \\
&$^1B_u (\Ryd; n \ra 3p)$ & 7.84$^d$ \\
&$^3A_u (\Val; n \ra \pis)$ & 2.49$^a$ \\
&$^3B_g (\Val; n \ra \pis)$ & 3.99$^a$ \\
&$^3B_u (\Val; \pi \ra \pis)$ & 5.17$^a$ \\
&$^3A_g (\Val; \pi \ra \pis)$ & 6.33$^a$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (14e,12o) active space including valence $\pi$, two $n_\text{O}$, $\si_\text{CC}$, $\si_\text{CO}$, $\si^*_\text{CC}$ and $\si^*_\text{CO}$ orbitals.
$^b$Using reference (14e,13o) active space including valence $\pi$, two $n_\text{O}$, $\si_\text{CC}$, $\si_\text{CO}$, $\si^*_\text{CC}$, $\si^*_\text{CO}$ and $3p_z$ orbitals.
$^c$Non-negligible doubly-excited and Rydberg character.
$^d$Using reference (14e,13o) active space including valence $\pi$, two $n_\text{O}$, $\si_\text{CC}$, $\si_\text{CO}$, $\si^*_\text{CC}$, $\si^*_\text{CO}$ and $3p_x$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of imidazole.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Imidazole &$^1A'' (\Ryd; \pi \ra 3s)$ &5.97$^a$,5.93$^b$ \\
&$^1A' (\Val; \pi \ra \pis)$ &6.86$^c$,6.81$^d$,6.73$^e$ \\
&$^1A'' (\Val; n \ra \pis)$ &6.97$^f$,6.96$^b$ \\
&$^1A' (\Ryd; \pi \ra 3p)$ &7.08$^d$,7.00$^e$ \\
&$^3A' (\Val; \pi \ra \pis)$ &4.98$^c$,4.86$^e$ \\
&$^3A'' (\Ryd; \pi \ra 3s)$ &5.93$^a$,5.91$^b$ \\
&$^3A' (\Val; \pi \ra \pis)$ &6.09$^c$,5.91$^e$ \\
&$^3A'' (\Val; n \ra \pis)$ &6.49$^f$,6.48$^b$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (6e,6o) active space including valence $\pi$ and 3s orbitals.
$^b$Using reference (8e,7o) active space including valence $\pi$, $n_\text{N}$ and 3s orbitals.
$^c$Using reference (6e,5o) active space including valence $\pi$ orbitals.
$^d$Using reference (6e,6o) active space including valence $\pi$ and one $3p_z$ orbitals.
$^e$Using reference (6e,9o) active space including valence $\pi$ and four $3p_z$ orbitals.
$^f$Using reference (8e,6o) active space including valence $\pi$ and $n_\text{N}$ orbitals.
$^g$Using reference (8e,9o) active space including valence $\pi$, $n_\text{N}$, two $3p_z$ and 3s orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of isobutene.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Isobutene &$^1B_1 (\Ryd; \pi \ra 3s)$ &6.63$^a$ \\
&$^1A_1 (\Ryd; \pi \ra 3p)$ &7.20$^b$ \\
&$^3A_1 (\Val; (\pi \ra \pis)$ &4.61$^c$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (4e,5o) active space including valence $\pi$, $\si_\text{CC}$, $\si^*_\text{CC}$ and 3s orbitals.
$^b$Using reference (4e,5o) active space including valence $\pi$, $\si_\text{CC}$, $\si^*_\text{CC}$ and $3p_x$ orbitals.
$^c$Using reference (4e,4o) active space including valence $\pi$, $\si_\text{CC}$ and $\si^*_\text{CC}$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of methylenecyclopropene.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Methylenecyclopropene& $^1B_2 (\Val; \pi \ra \pis)$ &4.37$^a$ \\
&$^1B_1 (\Ryd; \pi \ra 3s)$ &5.51$^b$,5.49$^c$ \\
&$^1A_2 (\Ryd; \pi \ra 3p)$ &6.00$^c$ \\
&$^1A_1(\Val; \pi \ra \pis)$ &6.33$^d$,6.36$^e$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ &3.66$^a$ \\
&$^3A_1 (\Val; \pi \ra \pis)$ &4.87$^d$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (4e,4o) active space.
$^b$Using reference (6e,6o) active space.
$^c$Using reference (4e,5o) active space.
$^d$Using reference (4e,6o) active space.
$^e$Using reference (4e,7o) active space.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of propynal.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Propynal & $^1A'' (\Val; n \ra \pis)$ &3.95$^a$ \\
&$^1A'' (\Val; \pi \ra \pis)$ & 5.50$^a$ \\
&$^3A'' (\Val; n \ra \pis)$ & 3.59$^a$ \\
&$^3A' (\Val; \pi \ra \pis)$ & 4.63$^b$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (8e,7o) active space including valence $\pi$ and $n_\text{O}$ orbitals.
$^b$Using reference (6e,6o) active space including valence $\pi$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of pyrazine.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Pyrazine &$^1B_{3u} (\Val; n \ra \pis)$ & 4.17$^a$ \\
&$^1A_{u} (\Val; n \ra \pis)$ & 4.77$^a$ \\
&$^1B_{2u} (\Val; \pi \ra \pis)$ & 5.32$^b$,5.37$^c$ \\
&$^1B_{2g} (\Val; n \ra \pis)$ & 5.88$^a$ \\
&$^1A_{g} (\Ryd; n \ra 3s)$ & 6.70$^d$\\
&$^1B_{1g} (\Val; n \ra \pis)$ & 6.75$^a$ \\
&$^1B_{1u} (\Val; \pi \ra \pis)$ & 6.38$^b$,6.31$^e$,6.81$^f$ \\
&$^1B_{1g} (\Ryd; \pi \ra 3s)$ & 7.33$^g$ \\
&$^1B_{2u} (\Ryd; n \ra 3p)$ & 7.25$^c$ \\
&$^1B_{1u} (\Ryd; n \ra 3p)$ & 7.42$^e$ \\
&$^1B_{1u} (\Val; \pi \ra \pis)$ & 7.29$^b$,6.96$^e$,8.25$^f$\\
&$^3B_{3u} (\Val; n \ra \pis)$ & 3.56$^a$ \\
&$^3B_{1u} (\Val; \pi \ra \pis)$ & 4.68$^b$,4.57$^f$ \\
&$^3B_{2u} (\Val; (\pi \ra \pis)$ & 4.42$^b$ \\
&$^3A_{u} (\Val; n \ra \pis)$ & 4.75$^a$ \\
&$^3B_{2g} (\Val; n \ra \pis)$ & 5.21$^a$ \\
&$^3B_{1u} (\Val; \pi \ra \pis)$ & 5.43$^b$,5.35$^f$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (10e,8o) active space including valence $\pi$ and $n_\text{N}$ orbitals.
$^b$Using reference (6e,6o) active space including valence $\pi$ orbitals.
$^c$Using reference (10e,9o) active space including valence $\pi$, $n_\text{N}$ and $3p_y$ orbitals.
$^d$Using reference (10e,9o) active space including valence $\pi$, $n_\text{N}$ and 3s orbitals.
$^e$Using reference (10e,9o) active space including valence $\pi$, $n_\text{N}$ and $3p_z$ orbitals.
$^f$Using reference (6e,9o) active space including valence $\pi$ and three $3p_x$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of pyridazine.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Pyridazine &$^1B_1 (\Val; n \ra \pis)$ & 3.80$^a$ \\
&$^1A_2 (\Val; n \ra \pis)$ & 4.40$^a$ \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 5.58$^b$ \\
&$^1A_2 (\Val; n \ra \pis)$ & 5.88$^a$ \\
&$^1B_2 (\Ryd; n \ra 3s)$ & 6.21$^c$ \\
&$^1B_1 (\Val; n \ra \pis)$ & 6.64$^a$ \\
&$^1B_2 (\Val; \pi \ra \pis)$ & 7.82$^b$,7.19$^d$,7.10$^e$ \\
&$^3B_1 (\Val; n \ra \pis)$ & 3.13$^a$ \\
&$^3A_2 (\Val; n \ra \pis)$ & 4.14$^a$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 4.65$^b$,4.55$^d$,4.49$^e$ \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 4.94$^a$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (10e,8o) active space including valence $\pi$ and $n_\text{N}$ orbitals.
$^b$Using reference (6e,6o) active space including valence $\pi$ orbitals.
$^c$Using reference (10e,9o) active space including valence $\pi$, $n_\text{N}$ and 3s orbitals.
$^d$Using reference (6e,9o) active space including valence $\pi$, $n_\text{N}$ and three $3p_x$ orbitals.
$^e$Using reference (6e,12o) active space including valence $\pi$, $n_\text{N}$ and six $3p_x$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of pyridine.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Pyridine &$^1B_1 (\Val; n \ra \pis)$ & 5.17$^a$,5.15$^b$ \\
&$^1B_2 (\Val; \pi \ra \pis)$ & 5.44$^c$,5.31$^d$ \\
&$^1A_2 (\Val; n \ra \pis)$ & 5.32$^a$,5.29$^e$ \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 6.69$^c$ \\
&$^1A_1 (\Ryd; n \ra 3s)$ & 6.99$^e$ \\
&$^1A_2 (\Ryd; \pi \ra 3s)$ & 6.96$^f$,6.86$^e$\\
&$^1B_2 (\Val; \pi \ra \pis)$ & 8.61$^a$,7.83$^d$ \\
&$^1B_1 (\Ryd; \pi \ra 3p)$ & 7.57$^g$,7.45$^b$ \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 6.97$^c$ \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 4.60$^c$ \\
&$^3B_1 (\Val; n \ra \pis)$ & 4.58$^a$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 4.90$^c$,4.88$^d$ \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 5.19$^c$ \\
&$^3A_2 (\Val; n \ra \pis)$ & 5.33$^a$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 7.00$^c$,6.29$^d$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (8e,7o) active space including valence $\pi$ and $n_\text{N}$ orbitals.
$^b$Using reference (8e,8o) active space including valence $\pi$, $n_\text{N}$ and $3p_y$ orbitals.
$^c$Using reference (6e,6o) active space including valence $\pi$ orbitals.
$^d$Using reference (6e,10o) active space including valence $\pi$ and four $3p_x$ orbitals.
$^e$Using reference (8e,8o) active space including valence $\pi$, $n_\text{N}$ and 3s orbitals.
$^d$Using reference (6e,8o) active space including valence $\pi$ and 3s orbitals.
$^g$Using reference (6e,7o) active space including valence $\pi$ and $3p_y$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of pyrimidine.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Pyrimidine &$^1B_1 (\Val; n \ra \pis)$ & 4.55$^a$ \\
&$^1A_2 (\Val; n \ra \pis)$ & 4.84$^a$ \\
&$^1B_2 (\Val; \pi \ra \pis)$ & 5.71$^b$,5.57$^d$,5.53$^e$ \\
&$^1A_2 (\Val; n \ra \pis)$ & 6.02$^a$ \\
&$^1B_1 (\Val; n \ra \pis)$ & 6.40$^a$ \\
&$^1B_2 (\Ryd; n \ra 3s)$ & 6.77$^c$ \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 7.47$^b$,7.11$^e$ \\
&$^3B_1 (\Val; n \ra \pis)$ & 4.17$^a$ \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 4.84$^b$,4.67$^e$ \\
&$^3A_2 (\Val; n \ra \pis)$ & 4.72$^a$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 5.08$^b$,5.01$^e$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (10e,8o) active space including valence $\pi$ and $n_\text{N}$ orbitals
$^b$Using reference (6e,6o) active space including valence $\pi$ orbitals.
$^c$Using reference (10e,9o) active space including valence $\pi$, $n_\text{N}$ and 3s orbitals.
$^d$Using reference (6e,9o) active space including valence $\pi$ and three $3p_x$ orbitals.
$^e$Using reference (6e,11o) active space including valence $\pi$ and five $3p_x$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of pyrrole.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Pyrrole &$^1A_2 (\Ryd; \pi \ra 3s)$ & 5.51$^a$ \\
&$^1B_1 (\Ryd; \pi \ra 3p)$ & 6.32$^b$ \\
&$^1A_2 (\Ryd; \pi \ra 3p)$ & 6.44$^c$ \\
&$^1B_2 (\Val; (\pi \ra \pis)$ & 6.48$^{e,f}$ \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 6.53$^d$ \\
&$^1B_2 (\Ryd; \pi \ra 3p)$ & 6.50$^d$,6.62$^{e,f}$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 4.74$^d$ \\
&$^3A_2 (\Ryd; \pi \ra 3s)$ & 5.49$^a$ \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 5.56$^d$ \\
&$^3B_1 (\Ryd; \pi \ra 3p)$ & 6.28$^b$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (6e,6o) active space including valence $\pi$ and 3s orbitals.
$^b$Using reference (6e,6o) active space including valence $\pi$ and $3p_y$ orbitals.
$^c$Using reference (6e,7o) active space including valence $\pi$, 3s and $3p_z$ orbitals.
$^d$Using reference (6e,5o) active space including valence $\pi$ orbitals.
$^e$Using reference (6e,6o) active space including valence $\pi$ and $3p_x$ orbitals.
$^f$Increasing the $\pi$ $3p_x$ active space leads to strong mixing in the zeroth-order wavefunction requiring a multi-state treatment (see Roos et al., J. Chem. Phys. 2002, 116, 7526--7536).
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of tetrazine.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Tetrazine &$^1B_{3u} (\Val; n \ra \pis)$ & 2.35$^a$ \\
&$^1A_{u} (\Val; n \ra \pis)$ & 3.58$^a$ \\
&$^1A_{g} (\Val; n,n \ra \pis, \pis)$ & 4.61$^a$ \\
&$^1B_{1g} (\Val; n \ra \pis)$ & 4.95$^a$ \\
&$^1B_{2u} (\Val; \pi \ra \pis)$ & 5.56$^b$ \\
&$^1B_{2g} (\Val; n \ra \pis)$ & 5.63$^a$ \\
&$^1A_{u} (\Val; n \ra \pis)$ & 5.62$^a$ \\
&$^1B_{3g} (\Val; n,n \ra \pis, \pis)$ & 6.15$^a$ \\
&$^1B_{2g} (\Val; n \ra \pis)$ & 6.13$^a$ \\
&$^1B_{1g} (\Val; n \ra \pis)$ & 6.76$^a$ \\
&$^3B_{3u} (\Val; n \ra \pis)$ & 1.73$^a$ \\
&$^3A_{u} (\Val; n \ra \pis)$ & 3.36$^a$ \\
&$^3B_{1g} (\Val; n \ra \pis)$ & 4.24$^a$ \\
&$^3B_{1u} (\Val; \pi \ra \pis)$ & 4.80$^b$,4.70$^a$ \\
&$^3B_{2u} (\Val; \pi \ra \pis)$ & 4.58$^b$ \\
&$^3B_{2g} (\Val; n \ra \pis)$ & 5.27$^a$ \\
&$^3A_{u} (\Val; n \ra \pis)$ & 5.13$^a$ \\
&$^3B_{3g} (\Val; n,n \ra \pis, \pis)$ & 5.51$^a$ \\
&$^3B_{1u} (\Val; \pi \ra \pis)$ & 5.64$^b$,5.56$^c$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (14e,10o) active space including valence $\pi$ and $n_\text{N}$ orbitals.
$^b$Using reference (6e,6o) active space including valence $\pi$ orbitals.
$^c$Using reference (6e,9o) active space including valence $\pi$ and three $3p_x$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of thioacetone.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Thioacetone &$^1A_2 (\Val; n \ra \pis)$ & 2.55$^a$ \\
&$^1B_2 (\Ryd; n \ra 4s)$ & 5.72$^b$ \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 6.09$^c$,6.24$^d$ \\
&$^1B_2 (\Ryd; n \ra 4p)$ & 6.62$^b$ \\
&$^1A_1 (\Ryd; n \ra 4p)$ & 6.52$^d$ \\
&$^3A_2 (\Val; n \ra \pis)$ & 2.32$^a$ \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 3.48$^c$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (6e,5o) active space including valence $\pi$, $n_\text{O}$, $\si_\text{CO}$ and $\si^*_\text{CO}$ orbitals.
$^b$Using reference (6e,7o) active space including valence $\pi$, $n_\text{O}$, $\si_\text{CO}$, $\si^*_\text{CO}$, 4s and $4p_z$ orbitals.
$^c$Using reference (4e,4o) active space including valence $\pi$, $\si_\text{CO}$ and $\si^*_\text{CO}$ orbitals.
$^d$Using reference (6e,6o) active space including valence $\pi$, $n_\text{O}$, $\si_\text{CO}$, $\si^*_\text{CO}$ and $4p_y$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of thiophene.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Thiophene &$^1A_1 (\Val; \pi \ra \pis)$ & 5.84$^a$ \\
&$^1B_2 (\Val; \pi \ra \pis)$ & 5.64$^a$,5.54$^b$,6.10$^c$ \\
&$^1A_2 (\Ryd; \pi \ra 3s)$ & 6.20$^d$ \\
&$^1B_1 (\Ryd; \pi \ra 3p)$ & 6.19$^e$ \\
&$^1A_2 (\Ryd; \pi \ra 3p)$ & 6.40$^e$,6.52$^f$ \\
&$^1B_1 (\Ryd; \pi \ra 3s)$ & 6.73$^d$, 6.71$^f$ \\
&$^1B_2 (\Ryd; \pi \ra 3p)$ & 7.42$^b$,7.25$^c$ \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 7.39$^{a,h}$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 4.13$^a$ \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 4.84$^a$ \\
&$^3B_1 (\Ryd; \pi \ra 3p)$ & 5.98$^e$ \\
&$^3A_2 (\Ryd; \pi \ra 3s)$ & 6.14$^d$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (6e,5o) active space including valence $\pi$ orbitals.
$^b$Using reference (6e,6o) active space including valence $\pi$ and $3p_x$ orbitals.
$^c$Using reference (6e,7o) active space including valence $\pi$ and two $3p_x$ orbitals.
$^d$Using reference (6e,6o) active space including valence $\pi$ and 3s orbitals.
$^e$Using reference (6e,6o) active space including valence $\pi$ and $3p_y$ orbitals.
$^f$Using reference (6e,7o) active space including valence $\pi$, 3s and $3p_y$ orbitals.
$^g$Using reference (6e,8o) active space including valence $\pi$, 3s, $3p_y$ and $3p_z$ orbitals.
$^h$Strong double-excitation character.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of thiopropynal.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2$^a$ \\
\hline
Thiopropynal &$^1A'' (\Val; n \ra \pis)$ & 2.05 \\
&$^3A'' (\Val; n \ra \pis)$ & 1.81 \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$All calculations using reference (8e,7o) active space including valence $\pi$ and $n_\text{O}$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\begin{table}
\caption{NEVPT2/aug-cc-pVTZ vertical transition energies (in eV) of triazine.}
\begin{tabularx}{\textwidth}{XXX}
\hline
Molecule & State & NEVPT2 \\
\hline
Triazine &$^1A_1'' (\Val; n \ra \pis)$ & 4.61$^a$ \\
&$^1A_2'' (\Val; n \ra \pis)$ & 4.89$^a$ \\
&$^1E'' (\Val; n \ra \pis)$ & 4.88$^a$ \\
&$^1A_2' (\Val; \pi \ra \pis)$ & 6.10$^b$,6.15$^c$,5.95$^d$ \\
&$^1A_1' (\Val; \pi \ra \pis)$ & 7.06$^b$,7.30$^d$ \\
&$^1E' (\Ryd; n \ra 3s)$ & 7.45$^c$ \\
&$^1E'' (\Val; n \ra \pis)$ & 7.98$^a$ \\
&$^1E' (\Val; \pi \ra \pis)$ & 7.74$^b$,8.34$^d$ \\
&$^3A_2'' (\Val; n \ra \pis)$ & 4.51$^a$ \\
&$^3E'' (\Val; n \ra \pis)$ & 4.61$^a$ \\
&$^3A_1'' (\Val; n \ra \pis)$ & 4.71$^a$ \\
&$^3A_1' (\Val; \pi \ra \pis)$ & 5.20$^b$,5.05$^d$ \\
&$^3E' (\Val; \pi \ra \pis)$ & 5.83$^b$,5.73$^d$ \\
&$^3A_2' (\Val; (\pi \ra \pis)$ & 5.83$^b$,6.36$^d$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (12e,9o) active space including valence $\pi$ and $n_\text{N}$ orbitals.
$^b$Using reference (6e,6o) active space including valence $\pi$ orbitals.
$^c$Using reference (12e,10o) active space including valence $\pi$, $n_\text{N}$ and 3s orbitals.
$^d$Using reference (6e,9o) active space including valence $\pi$ and three $3p_x$ orbitals.
\end{footnotesize}
\end{flushleft}
\end{table}
\clearpage
\section{Selected CI results}
\begin{landscape}
\begin{footnotesize}
\begin{longtable}{p{3.5cm}p{3.5cm}p{2cm}p{1.2cm}p{2.8cm}p{2cm}p{1.2cm}p{2.8cm}}
\caption{
Vertical excitations (in eV) for various states of the studied molecules computed with an extrapolated SCI method (exFCI).
The number of determinants $N_\text{det}$ of the largest SCI wave functions and their corresponding excitation energies are also reported.
The extrapolation error is estimated as the difference in excitation energy between the largest SCI wave function and its corresponding extrapolated value.
\label{tab:sCI}}
\\
\hline
Molecule & Transition & \mc{3}{c}{\Pop} & \mc{3}{c}{\AVDZ} \\
\cline{3-5} \cline{6-8}
& & $\Ndet$ & SCI & exFCI & $\Ndet$ & SCI & exFCI \\
\hline
\endfirsthead
\hline
Molecule & Transition & \mc{3}{c}{\Pop} & \mc{3}{c}{\AVDZ} \\
\cline{3-5} \cline{6-8}
& & $\Ndet$ & SCI & exFCI & $\Ndet$ & SCI & exFCI \\
\hline
\endhead
\hline \multicolumn{8}{r}{{Continued on next page}} \\
\endfoot
\hline
\endlastfoot
Acetone & $^1A_2 (\Val; n \ra \pis)$ & $26\,526\,782$ & $4.55$ & $4.60\pm0.05$ \\
% & $^1B_2 (\Ryd; n \ra 3s)$ & $25\,1675\,94$ & $6.91$ & $6.83\pm0.08$ \\ %TO BE CHECKED !!!!!
% & $^1A_2 (\Ryd; n \ra 3p)$ & $$ & $$ & $$ \\
% & $^1A_1 (\Ryd; n \ra 3p)$ & $$ & $$ & $$ \\
% & $^1B_2 (\Ryd; n \ra 3p)$ & $$ & $$ & $$ \\
& $^3A_2 (\Val; n \ra \pis)$ & $26\,553\,941$ & $4.22$ & $4.18\pm0.04$ \\
% & $^3A_1 (\Val; \pi \ra \pis)$ & $$ & $$ & $$ \\
Acrolein & $^1A'' (\Val; n \ra \pis)$ & $23\,273\,572$ & $3.84$ & $3.85\pm0.01$ \\
% & $^1A' (\Val; \pi \ra \pis)$ & $$ & $$ & $$ \\
% & $^1A'' (\Val; n \ra \pis)$ & $$ & $$ & $$ \\
% & $^1A' (\Ryd; n \ra 3s)$ & $$ & $$ & $$ \\
& $^3A'' (\Val; n \ra \pis)$ & $26\,531\,491$ & $3.59$ & $3.60\pm0.01$
& $15\,827\,189$ & $3.58$ & $3.51\pm0.07$ \\
& $^3A' (\Val; \pi \ra \pis)$ & $37\,480\,261$ & $4.01$ & $3.98\pm0.03$
& $15\,827\,189$ & $4.05$ & $3.96\pm0.09$ \\
% & $^3A' (\Val; \pi \ra \pis)$ & $$ & $$ & $$ \\
% & $^3A'' (\Ryd; \pi \ra 3s)$ & $$ & $$ & $$ \\
Butadiene & $^1B_u (\Val; \pi \ra \pis)$ & $20\,552\,493$ & $6.43$ & $6.41\pm0.02$ \\
% & $^1B_g (\Ryd; \pi \ra 3s)$ & $$ & $$ & $$ \\
% & $^1A_g (\Val; \pi \ra \pis)$ & $92\,506\,300$ & $6.59$ & $6.55\pm0.04$
% & $59\,594\,588$ & $6.58$ & $6.51\pm0.07$ \\
% & $^1A_u (\Ryd; \pi \ra 3p)$ & $$ & $$ & $$ \\
& $^1A_u (\Ryd; \pi \ra 3p)$ & $20\,552\,493$ & $6.96$ & $6.95\pm0.01$
& $12\,521\,242$ & $6.72$ & $6.72\pm0.00$ \\
% & $^1B_u (\Ryd; \pi \ra 3p)$ & $$ & $$ & $$ \\
& $^3B_u (\Val; \pi \ra \pis)$ & $49\,847\,526$ & $3.40$ & $3.37\pm0.03$ \\
& $^3A_g (\Val; \pi \ra \pis)$ & & &
& $17\,235\,280$ & $6.29$ & $6.21\pm0.08$ \\
& $^3B_g (\Val; \pi \ra 3s)$ & $49\,847\,526$ & $6.43$ & $6.40\pm0.03$ \\
Cyanoacetylene & $^1\Sigma^- (\Val; \pi \ra \pis)$ & $21\,269\,249$ & $6.01$ & $6.02\pm0.01$
& $11\,023\,351$ & $5.93$ & $5.84\pm0.09$ \\
& $^1\Delta (\Val; \pi \ra \pis)$ & $21\,269\,249$ & $6.29$ & $6.28\pm0.01$
& $11\,023\,351$ & $6.19$ & $6.14\pm0.05$ \\
& $^3\Sigma^+ (\Val; \pi \ra \pis)$ & $18\,198\,954$ & $4.48$ & $4.45\pm0.03$
& $25\,646\,703$ & $4.47$ & $4.41\pm0.06$ \\
& $^3\Delta (\Val; \pi \ra \pis)$ & $18\,198\,954$ & $5.35$ & $5.32\pm0.03$
& $25\,646\,703$ & $5.28$ & $5.20\pm0.08$ \\
& $^1A'' [\Fl] (\Val; \pi \ra \pis)$ & $104\,485\,975$ & $3.70$ & $3.67\pm0.03$
& $62\,248\,690$ & $3.61$ & $3.50\pm0.02$ \\
Cyanoformaldehyde & $^1A'' (\Val; n \ra \pis)$ & $17\,778\,047$ & $3.94$ & $3.92\pm0.02$
& $19\,020\,785$ & $3.93$ & $3.98\pm0.05$ \\
& $^1A'' (\Val; \pi \ra \pis)$ & $17\,778\,047$ & $6.67$ & $6.60\pm0.07$
& $19\,020\,785$ & $6.57$ & $6.58\pm0.01$ \\
& $^3A'' (\Val; n \ra \pis)$ & $21\,011\,221$ & $3.54$ & $3.48\pm0.06$
& $48\,532\,729$ & $3.51$ & $3.52\pm0.01$ \\
& $^3A' (\Val; \pi \ra \pis)$ & & &
& $48\,5327\,29$ & $5.10$ & $5.07\pm0.03$ \\
Cyanogen & $^1\Sigma_u^- (\Val; \pi \ra \pis)$ & $12\,1991\,55$ & $6.61$ & $6.58\pm0.03$
& $20\,9495\,13$ & $6.52$ & $6.44\pm0.08$ \\
& $^1\Delta_u (\Val; \pi \ra \pis)$ & $12\,1991\,55$ & $6.89$ & $6.87\pm0.02$
& $20\,9495\,13$ & $6.78$ & $6.74\pm0.04$ \\
& $^3\Sigma_u^+ (\Val; \pi \ra \pis)$ & $34\,1277\,36$ & $4.97$ & $4.91\pm0.06$
& $25\,7606\,68$ & $4.94$ & $4.87\pm0.07$ \\
& $^1\Sigma_u^- [\Fl] (\Val; \pi \ra \pis)$ & $21\,4163\,04$ & $5.36$ & $5.31\pm0.05$
& $28\,8841\,38$ & $5.17$ & $5.26\pm0.09$ \\
Cyclopropenone & $^1B_1 (\Val; n \ra \pis)$ & $48\,8976\,96$ & $4.40$ & $4.38\pm0.02$ \\
& $^1A_2 (\Val; n \ra \pis)$ & $24\,5411\,16$ & $5.70$ & $5.64\pm0.06$ \\
% & $^1B_2 (\Ryd; n \ra 3s)$ & $$ & $$ & $$ \\
% & $^1B_2 (\Val; \pi \ra \pis$) & $$ & $$ & $$ \\
% & $^1B_2 (\Ryd; n \ra 3p)$ & $$ & $$ & $$ \\
% & $^1A_1 (\Ryd; n \ra 3p)$ & $$ & $$ & $$ \\
% & $^1A_1 (\Val; \pi \ra \pis)$ & $$ & $$ & $$ \\
& $^3B_1 (\Val; n \ra \pis)$ & $24\,008\,328$ & $4.07$ & $4.00\pm0.07$ \\
& $^3B_2 (\Val; \pi \ra \pis)$ & $48\,311\,362$ & $4.95$ & $4.95\pm0.00$ \\
% & $^3A_2 (\Val; n \ra \pis)$ & $$ & $$ & $$ \\
% & $^3A_1 (\Val; \pi \ra \pis)$ & $$ & $$ & $$ \\
Cyclopropenethione & $^1A_2 (\Val; n \ra \pis)$ & $39\,385\,657$ & $3.46$ & $3.45\pm0.01$ \\
& $^1B_1 (\Val; n \ra \pis)$ & $39\,385\,657$ & $3.50$ & $3.44\pm0.05$ \\
& $^1B_2 (\Val; \pi \ra \pis)$ & $39\,385\,657$ & $4.68$ & $4.59\pm0.09$ \\
% & $^1B_2 (\Ryd; n \ra 3s)$ & $$ & $$ & $$ \\
% & $^1A_1 (\Val; \pi \ra \pis)$ & $$ & $$ & $$ \\
% & $^1B_2 (\Ryd; n \ra 3p)$ & $$ & $$ & $$ \\
& $^3A_2 (\Val; n \ra \pis)$ & $23\,904\,962$ & $3.32$ & $3.29\pm0.03$ \\
% & $^3B_1 (\Val; n \ra \pis)$ & $$ & $$ & $$ \\
& $^3B_2 (\Val; \pi \ra \pis)$ & $23\,904\,962$ & $4.06$ & $4.03\pm0.03$ \\
% & $^3A_1 (\Val; \pi \ra \pis)$ & $$ & $$ & $$ \\
Diacetylene & $^1\Sigma_u^- (\Val; \pi \ra \pis)$ & $18\,955\,451$ & $5.58$ & $5.52\pm0.06$
& $19\,192\,556$ & $5.45$ & $5.47\pm0.02$ \\
& $^1\Delta_u (\Val; \pi \ra \pis)$ & $18\,955\,451$ & $5.85$ & $5.84\pm0.01$
& $19\,192\,556$ & $5.45$ & $5.69\pm0.02$ \\
& $^3\Sigma_u^+ (\Val; \pi \ra \pis)$ & $13\,777\,757$ & $4.11$ & $4.04\pm0.07$
& $26\,668\,471$ & $4.11$ & $4.07\pm0.04$ \\
& $^3\Delta_u (\Val; \pi \ra \pis)$ & $13\,777\,757$ & $4.93$ & $4.94\pm0.01$
& $26\,668\,471$ & $4.87$ & $4.85\pm0.02$ \\
Glyoxal & $^1A_u (\Val; n \ra \pis)$ & $51\,656\,090$ & $2.96$ & $2.93\pm0.03$
& $34\,125\,394$ & $2.94$ & $2.93\pm0.01$ \\
& $^1B_g (\Val; n \ra \pis)$ & $24\,394\,242$ & $4.34$ & $4.28\pm0.06$ \\
% & $^1A_g (\Val; n,n \ra \pis,\pis)$ & $118\,275\,835$ & $5.69$ & $5.60\pm0.09$ \\
% & $^1B_g (\Val; n \ra \pis)$ & $$ & $$ & $$ \\
% & $^1B_u (\Ryd; n \ra 3p)$ & $$ & $$ & $$ \\
& $^3A_u (\Val; n \ra \pis)$ & $47\,693\,908$ & $2.58$ & $2.54\pm0.04$ \\
% & $^3B_g (\Val; n \ra \pis)$ & $$ & $$ & $$ \\
% & $^3B_u (\Val; \pi \ra \pis)$ & $$ & $$ & $$ \\
% & $^3A_g (\Val; \pi \ra \pis)$ & $$ & $$ & $$ \\
Isobutene & $^1B_1 (\Ryd; \pi \ra 3s)$ & $28\,095\,377$ & $6.86$ & $6.78\pm0.08$ \\
& $^1A_1 (\Ryd; \pi \ra 3p)$ & $59\,728\,169$ & $7.22$ & $7.16\pm0.02$ \\
& $^3A_1 \Val; (\pi \ra \pis)$ & $32\,440\,621$ & $4.54$ & $4.56\pm0.02$ \\
Methylenecyclopropene & $^1B_2 (\Val; \pi \ra \pis)$ & $51\,918\,524$ & $4.35$ & $4.32\pm0.03$ \\
% & $^1B_1 (\Ryd; \pi \ra \sigma^\star)$ & $$ & $$ & $$ \\
& $^1A_2 (\Ryd; \pi \ra 3p)$ & $25\,146\,911$ & $6.02$ & $5.92\pm0.10$ \\
& $^1A_1(\Val; \pi \ra \pis)$ & $31\,721\,213$ & $6.21$ & $6.20\pm0.01$ \\
& $^3B_2 (\Val; \pi \ra \pis)$ & $24\,379\,551$ & $3.50$ & $3.44\pm0.06$
& $43\,090\,114$ & $3.49$ & $3.45\pm0.04$ \\
& $^3A_1 (\Val; \pi \ra \pis)$ & $24\,379\,551$ & $4.77$ & $4.67\pm0.10$
& $43\,090\,114$ & $4.77$ & $4.79\pm0.02$ \\
Propynal & $^1A'' (\Val; n \ra \pis)$ & $48\,945\,252$ & $3.90$ & $3.84\pm0.06$
& $28\,249\,344$ & $3.92$ & $3.89\pm0.03$ \\
& $^1A'' (\Val; \pi \ra \pis)$ & $26\,554\,616$ & $5.72$ & $5.64\pm0.08$
& $28\,249\,344$ & $5.72$ & $5.63\pm0.09$ \\
& $^3A'' (\Val; n \ra \pis)$ & $23\,182\,284$ & $3.58$ & $3.54\pm0.04$ \\
& $^3A' (\Val; \pi \ra \pis)$ & $39\,375\,360$ & $4.52$ & $4.44\pm0.08$ \\
Thioacetone & $^1A_2 (\Val; n \ra \pis)$ & $26\,515\,070$ & $2.56$ & $2.61\pm0.05$ \\
% & $^1B_2 (\Ryd; n \ra 4s)$ & $??$ & $??$ & $5.60\pm0.04$ \\
% & $^1A_1 (\Val; \pi \ra \pis)$ & $$ & $$ & $$ \\
% & $^1A_1 (\Ryd; n \ra 4p)$ & $$ & $$ & $$ \\
% & $^1B_2 (\Ryd; n \ra 4p)$ & $$ & $$ & $$ \\
& $^3A_2 (\Val; n \ra \pis)$ & $63\,669\,401$ & $2.36$ & $2.36\pm0.00$ \\
% & $^3A_1 (\Val; \pi \ra \pis)$ & $$ & $$ & $$ \\
Thiopropynal & $^1A'' (\Val; n \ra \pis)$ & $15\,782\,429$ & $2.07$ & $2.08\pm0.01$ \\
% & $^3A'' (\Val; n \ra \pis)$ & $$ & $$ & $$ \\
\end{longtable}
\end{footnotesize}
\begin{flushleft}\begin{footnotesize}
%$^a${CI convergence too slow to provide reliable estimate.}
\end{footnotesize}\end{flushleft}
\end{landscape}
\clearpage
\section{Benchmarks}
\subsection{Raw data}
\clearpage
\begin{landscape}
\renewcommand*{\arraystretch}{.55}
\LTcapwidth=\textwidth
\begin{footnotesize}
\begin{longtable}{p{3.73cm}p{3.6cm}p{.55cm}|p{1.2cm}p{1.2cm}p{1.2cm}p{1.2cm}p{1.2cm}p{1.6cm}p{1.2cm}p{1.2cm}}\\
\caption{Comparisons between the TBE(FC)/{\AVTZ} benchmark (see Table 11) and the results obtained with various computational
approaches using the same basis set. STEOM stands for STEOM-CCSD and CC(3) for CCSDR(3).} \label{Table-SI-b1}\\
\hline
Compound & State & TBE & CIS(D) & CC2 & CCSD & STEOM & CC(3) &CCSDT-3& CC3& ADC(2) \\
\hline
\endfirsthead
\hline
Compound & State & TBE & CIS(D) & CC2 & CCSD & STEOM & CC(3) &CCSDT-3& CC3& ADC(2) \\
\hline
\endhead
\hline \multicolumn{11}{r}{{Continued on next page}} \\
\endfoot
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\endlastfoot
Acetone &$^1A_2 (\Val; n \ra \pis)$ & 4.47 &4.51 &4.55 &4.54& 4.40 &4.48 &4.49 &4.48 &4.37 \\
&$^1B_2 (\mathrm{R}; n \ra 3s)$ & 6.46 &5.91 &5.91 &6.59& 6.62 &6.46 &6.50 &6.43 &5.87 \\
&$^1A_2 (\mathrm{R}; n \ra 3p)$ & 7.47 &6.83 &6.84 &7.57& &7.47 &7.51 &7.45 &6.81 \\
&$^1A_1 (\mathrm{R}; n \ra 3p)$ & 7.51 &7.04 &6.89 &7.63& 7.68 &7.52 &7.55 &7.48 &6.85 \\
&$^1B_2 (\mathrm{R}; n \ra 3p)$ & 7.62 &6.93 &7.02 &7.72& &7.61 &7.65 &7.59 &6.99 \\
&$^3A_2 (\Val; n \ra \pis)$ & 4.13 &4.15 &4.16 &4.15& 4.05 & & &4.15 &4.00 \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 6.25 &6.50 &6.50 &6.19& 6.05 & & &6.28 &6.37 \\
Acrolein &$^1A'' (\Val; n \ra \pis)$ & 3.78 &3.89 &3.85 &3.91& 3.85 &3.80 &3.78 &3.74 &3.68 \\
&$^1A' (\Val; \pi \ra \pis)$ & 6.69 &6.88 &6.80 &6.87& &6.69 &6.71 &6.65 &6.74 \\
&$^1A'' (\Val; n \ra \pis)$ & \emph{6.72} &7.76 &6.68 &7.27& 6.98 &6.94 &6.89 &6.75 &6.59 \\
&$^1A' (\mathrm{R}; n \ra 3s)$ & 7.08 &6.92 &6.40 &7.24& 7.25 &7.12 &7.15 &7.07 &6.35 \\
&$^3A'' (\Val; n \ra \pis)$ & 3.51 &3.56 &3.49 &3.55& 3.48 & & &3.46 &3.33 \\
&$^3A' (\Val; \pi \ra \pis)$ & 3.94 &4.14 &4.06 &3.88& 3.72 & & &3.94 &4.05 \\
&$^3A' (\Val; \pi \ra \pis)$ & 6.18 &6.42 &6.37 &6.14& 6.00 & & &6.19 &6.31 \\
&$^3A'' (\Val; n \ra \pis)$ & \emph{6.54} & &6.55 &7.09& & & &6.61 &6.47 \\
Benzene &$^1B_{2u} (\Val; \pi \ra \pis)$ & 5.06 &5.32 &5.26 &5.20& 5.01 &5.14 &5.11 &5.09 &5.27 \\
&$^1B_{1u} (\Val; \pi \ra \pis)$ & 6.45 &6.61 &6.48 &6.50& 6.51 &6.47 &6.45 &6.44 &6.45 \\
&$^1E_{1g} (\mathrm{R}; \pi \ra 3s)$ & 6.52 &6.57 &6.47 &6.58& 6.65 &6.54 &6.54 &6.52 &6.52 \\
&$^1A_{2u} (\mathrm{R}; \pi \ra 3p)$ & 7.08 &7.08 &7.00 &7.12& 7.17 &7.10 &7.09 &7.08 &7.06 \\
&$^1E_{2u} (\mathrm{R}; \pi \ra 3p)$ & 7.15 &7.14 &7.06 &7.20& &7.17 &7.16 &7.15 &7.12 \\
&$^3B_{1u} (\Val; \pi \ra \pis)$ & 4.16 &4.47 &4.37 &4.00& & & &4.18 &4.37 \\
&$^3E_{1u}(\Val; \pi \ra \pis)$ & 4.85 &5.12 &5.08 &4.93& 4.88 & & &4.86 &5.07 \\
&$^3B_{2u} (\Val; \pi \ra \pis)$ & 5.81 &5.95 &5.89 &5.77& 5.78 & & &5.81 &5.87 \\
Butadiene &$^1B_u (\Val; \pi \ra \pis)$ & 6.22 &6.24 &6.16 &6.35& 6.33 &6.21 &6.24 &6.22 &6.12 \\
&$^1B_g (\mathrm{R}; \pi \ra 3s)$ & 6.33 &6.34 &6.26 &6.40& 6.38 &6.33 &6.34 &6.33 &6.31 \\
&$^1A_g (\Val; \pi \ra \pis)$ & 6.50 &7.35 &7.09 &7.12& &6.86 &6.76 &6.67 &7.14 \\
&$^1A_u (\mathrm{R}; \pi \ra 3p)$ & 6.64 &6.65 &6.57 &6.71& 6.69 &6.65 &6.66 &6.64 &6.63 \\
&$^1A_u (\mathrm{R}; \pi \ra 3p)$ & 6.80 &6.78 &6.70 &6.87& 6.92 &6.80 &6.81 &6.80 &6.76 \\
&$^1B_u (\mathrm{R}; \pi \ra 3p)$ & 7.68 &7.71 &7.63 &7.76& 7.76 &7.68 & &7.68 &7.48 \\
&$^3B_u (\Val; \pi \ra \pis)$ & 3.36 &3.55 &3.45 &3.29& 3.17 & & &3.36 &3.46 \\
&$^3A_g (\Val; \pi \ra \pis)$ & 5.20 &5.33 &5.30 &5.17& 5.03 & & &5.20 &5.27 \\
&$^3B_g (\mathrm{R}; \pi \ra 3s)$ & 6.29 &6.31 &6.21 &6.33& 6.42 & & &6.28 &6.27 \\
Cyanoacetylene &$^1\Sigma^- (\Val; \pi \ra \pis)$ & 5.80 &6.14 &6.03 &5.88& 5.87 &5.84 &5.81 &5.80 &5.99 \\
&$^1\Delta (\Val; \pi \ra \pis)$ & 6.07 &6.41 &6.30 &6.15& 6.20 &6.11 &6.09 &6.08 &6.25 \\
&$^3\Sigma^+ (\Val; \pi \ra \pis)$ & 4.44 &4.89 &4.80 &4.38& 4.35 & & &4.45 &4.77 \\
&$^3\Delta (\Val; \pi \ra \pis)$ & 5.21 &5.60 &5.50 &5.24& 5.22 & & &5.22 &5.46 \\
&$^1A'' [\mathrm{F}] (\Val; \pi \ra \pis)$ & 3.54 &3.83 &3.79 &3.58& 3.52 &3.58 &3.54 &3.54 &3.73 \\
Cyanoformaldehyde &$^1A'' (\Val; n \ra \pis)$ & 3.81 &3.98 &3.97 &3.94& 3.80 &3.87 &3.86 &3.83 &3.83 \\
&$^1A'' (\Val; \pi \ra \pis)$ & 6.46 &7.10 &6.74 &6.67& 6.56 &6.50 &6.47 &6.42 &6.73 \\
&$^3A'' (\Val; n \ra \pis)$ & 3.44 &3.54 &3.51 &3.49& 3.42 & & &3.46 &3.37 \\
&$^3A' (\Val; \pi \ra \pis)$ & 5.01 &5.43 &5.34 &4.97& 4.89 & & &5.01 &5.27 \\
Cyanogen & $^1\Sigma_u^- (\Val; \pi \ra \pis)$ & 6.39 &6.85 &6.72 &6.50& 6.46 &6.44 &6.40 &6.39 &6.67 \\
& $^1\Delta_u (\Val; \pi \ra \pis)$ & 6.66 &7.15 &7.02 &6.78& 6.80 &6.72 &6.68 &6.66 &6.95 \\
& $^3\Sigma_u^+ (\Val; \pi \ra \pis)$ & 4.91 &5.44 &5.35 &4.84& 4.81 & & &4.90 &5.31 \\
& $^1\Sigma_u^- [\mathrm{F}] (\Val; \pi \ra \pis)$ & 5.05 &5.61 &5.48 &5.13& 5.07 &5.14 &5.06 &5.06 &5.39 \\
Cyclopentadiene &$^1B_2 (\Val; \pi \ra \pis)$ & 5.56 &5.62 &5.52 &5.67& 5.59 &5.53 &5.56 &5.54 &5.49 \\
&$^1A_2 (\mathrm{R}; \pi \ra 3s)$ & 5.78 &5.75 &5.66 &5.83& 5.80 &5.78 &5.78 &5.77 &5.71 \\
&$^1B_1 (\mathrm{R}; \pi \ra 3p)$ & 6.41 &6.33 &6.26 &6.45& 6.44 &6.41 &6.41 &6.40 &6.31 \\
&$^1A_2 (\mathrm{R}; \pi \ra 3p)$ & 6.46 &6.37 &6.30 &6.50& 6.60 &6.46 &6.46 &6.45 &6.35 \\
&$^1B_2 (\mathrm{R}; \pi \ra 3p)$ & 6.56 &6.50 &6.42 &6.61& 6.65 &6.57 &6.56 &6.56 &6.48 \\
&$^1A_1 (\Val; \pi \ra \pis)$ & \emph{6.52} &7.63 &6.86 &6.96& &6.71 &6.66 &6.57 &6.91 \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 3.31 &3.52 &3.42 &3.24& 3.11 & & &3.32 &3.42 \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 5.11 &5.30 &5.36 &5.09& 4.79 & & &5.12 &5.23 \\
&$^3A_2 (\mathrm{R}; \pi \ra 3s)$ & 5.73 &5.73 &5.62 &5.78& 5.86 & & &5.73 &5.67 \\
&$^3B_1 (\mathrm{R}; \pi \ra 3p)$ & 6.36 &6.31 &6.22 &6.40& 6.47 & & &6.36 &6.27 \\
Cyclopropenone &$^1B_1 (\Val; n \ra \pis)$ & 4.26 &4.27 &4.01 &4.53& 4.18 &4.28 &4.31 &4.21 &3.88 \\
&$^1A_2 (\Val; n \ra \pis)$ & 5.55 &5.65 &5.65 &5.40& &5.59 &5.59 &5.57 &5.47 \\
&$^1B_2 (\mathrm{R}; n \ra 3s)$ & 6.34 &6.32 &5.84 &6.44& 6.36 &6.35 &6.38 &6.32 &5.79 \\
&$^1B_2 (\Val; \pi \ra \pis$) & 6.54 &6.60 &6.46 &6.82& &6.59 &6.61 &6.54 &6.33 \\
&$^1B_2 (\mathrm{R}; n \ra 3p)$ & 6.98 &6.48 &6.56 &7.09& 7.07 &6.98 & &6.96 &6.43 \\
&$^1A_1 (\mathrm{R}; n \ra 3p)$ & 7.02 &6.54 &6.47 &7.12& &7.02 &7.06 &7.00 &6.41 \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 8.28 &8.22 &8.28 &8.35& 8.19 &8.29 & &8.28 &8.10 \\
&$^3B_1 (\Val; n \ra \pis)$ & 3.93 &4.15 &3.73 &4.18& 4.13 & & &3.91 &3.62 \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 4.88 &5.26 &4.99 &4.91& 4.88 & & &4.89 &4.90 \\
&$^3A_2 (\Val; n \ra \pis)$ & 5.35 &5.96 &5.45 &5.40& 5.01 & & &5.37 &5.28 \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 6.79 &6.97 &6.42 &6.76& 6.39 & & &6.83 &6.84 \\
Cyclopropenethione &$^1A_2 (\Val; n \ra \pis)$ & 3.41 &3.45 &3.53 &3.51& 3.34 &3.43 &3.46 &3.43 &3.38 \\
&$^1B_1 (\Val; n \ra \pis)$ & 3.45 &3.56 &3.50 &3.84& &3.51 &3.56 &3.43 &3.37 \\
&$^1B_2 (\Val; \pi \ra \pis)$ & 4.60 &5.06 &4.91 &4.98& &4.69 &4.73 &4.64 &4.72 \\
&$^1B_2 (\mathrm{R}; n \ra 3s)$ & 5.34 &5.24 &5.22 &5.41& 5.45 &5.34 &5.38 &5.34 &5.17 \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 5.46 &5.47 &5.59 &5.55& &5.48 &5.52 &5.49 &5.36 \\
&$^1B_2 (\mathrm{R}; n \ra 3p)$ & 5.92 &5.93 &5.82 &6.03& 6.05 &5.93 &5.97 &5.93 &5.77 \\
&$^3A_2 (\Val; n \ra \pis)$ & 3.28 &3.34 &3.37 &3.34& 3.23 & & &3.30 &3.23 \\
&$^3B_1 (\Val; n \ra \pis)$ & 3.32 &3.55 &3.38 &3.69& 3.55 & & &3.31 &3.26 \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 4.01 &4.62 &4.24 &4.16& 4.05 & & &4.02 &4.12 \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 4.01 &4.12 &4.16 &3.97& 3.87 & & &4.03 &4.04 \\
Diacetylene &$^1\Sigma_u^- (\Val; \pi \ra \pis)$ & 5.33 &5.62 &5.51 &5.41& 5.37 &5.37 &5.35 &5.34 &5.49 \\
&$^1\Delta_u (\Val; \pi \ra \pis)$ & 5.61 &5.86 &5.76 &5.67& 5.64 &5.64 &5.62 &5.61 &5.72 \\
&$^3\Sigma_u^+ (\Val; \pi \ra \pis)$ & 4.10 &4.48 &4.39 &4.01& 4.05 & & &4.08 &4.37 \\
&$^3\Delta_u (\Val; \pi \ra \pis)$ & 4.78 &5.14 &5.03 &4.82& 4.87 & & &4.80 &5.01 \\
Furan &$^1A_2 (\mathrm{R}; \pi \ra 3s)$ & 6.09 &6.16 &6.06 &6.17& 6.15 &6.10 &6.09 &6.08 &6.12 \\
&$^1B_2 (\Val; \pi \ra \pis)$ & 6.37 &6.59 &6.45 &6.51& 6.45 &6.38 &6.37 &6.34 &6.47 \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 6.56 &7.01 &6.77 &6.85& &6.68 &6.65 &6.58 &6.76 \\
&$^1B_1 (\mathrm{R}; \pi \ra 3p)$ & 6.64 &6.67 &6.59 &6.71& 6.70 &6.65 &6.64 &6.63 &6.64 \\
&$^1A_2 (\mathrm{R}; \pi \ra 3p)$ & 6.81 &6.84 &6.75 &6.89& 6.93 &6.82 &6.81 &6.80 &6.82 \\
&$^1B_2 (\mathrm{R}; \pi \ra 3p)$ & 7.24 &7.34 &7.25 &7.32& 7.35 &7.25 & &7.23 &7.29 \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 4.20 &4.51 &4.43 &4.15& 4.17 & & &4.22 &4.41 \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 5.46 &5.69 &5.66 &5.47& 5.61 & & &5.48 &5.59 \\
&$^3A_2 (\mathrm{R}; \pi \ra 3s)$ & 6.02 &6.13 &6.01 &6.11& 6.20 & & &6.02 &6.08 \\
&$^3B_1 (\mathrm{R}; \pi \ra 3p)$ & 6.59 &6.64 &6.55 &6.66& 6.73 & & &6.59 &6.61 \\
Glyoxal &$^1A_u (\Val; n \ra \pis)$ & 2.88 &3.01 &2.91 &3.01& 2.86 &2.92 &2.91 &2.88 &2.83 \\
&$^1B_g (\Val; n \ra \pis)$ & 4.24 &4.46 &4.44 &4.42& 4.32 &4.32 &4.30 &4.27 &4.27 \\
&$^1A_g (\Val; n,n \ra \pis,\pis)$ & 5.61 & & & & & &7.26 &6.76 & \\
&$^1B_g (\Val; n \ra \pis)$ & 6.57 &7.01 &6.51 &7.12& &6.75 &6.73 &6.58 &6.50 \\
&$^1B_u (\mathrm{R}; n \ra 3p)$ & 7.71 &7.25 &7.16 &7.84& 7.94 &7.71 &7.74 &7.67 &7.18 \\
&$^3A_u (\Val; n \ra \pis)$ & 2.49 &2.59 &2.47 &2.56& 2.44 & & &2.49 &2.39 \\
&$^3B_g (\Val; n \ra \pis)$ & 3.89 &4.00 &3.96 &3.96& 3.88 & & &3.90 &3.82 \\
&$^3B_u (\Val; \pi \ra \pis)$ & 5.15 &5.47 &5.42 &5.10& 4.92 & & &5.17 &5.33 \\
&$^3A_g (\Val; \pi \ra \pis)$ & 6.30 &6.54 &6.56 &6.23& 6.13 & & &6.30 &6.45 \\
Imidazole &$^1A'' (\mathrm{R}; \pi \ra 3s)$ & 5.71 &5.81 &5.69 &5.80& 5.91 &5.73 &5.72 &5.71 &5.75 \\
&$^1A' (\Val; \pi \ra \pis)$ & 6.41 &6.73 &6.51 &6.59& 6.76 &6.47 &6.46 &6.41 &6.50 \\
&$^1A'' (\Val; n \ra \pis)$ & 6.50 &6.52 &6.47 &6.58& 6.66 &6.53 &6.51 &6.50 &6.51 \\
&$^1A' (\mathrm{R}; \pi \ra 3p)$ & \emph{6.83} &7.40 &6.41 &7.02& 6.92 &6.93 &6.91 &6.87 & \\
&$^3A' (\Val; \pi \ra \pis)$ & 4.73 &5.04 &4.94 &4.68& 4.66 & & &4.75 &4.92 \\
&$^3A'' (\mathrm{R}; \pi \ra 3s)$ & 5.66 &5.80 &5.66 &5.77& 5.87 & & &5.67 &5.72 \\
&$^3A' (\Val; \pi \ra \pis)$ & 5.74 &6.06 &5.94 &5.77& 5.60 & & &5.74 &5.93 \\
&$^3A'' (\Val; n \ra \pis)$ & 6.31 &6.47 &6.36 &6.40& 6.28 & & &6.33 &6.31 \\
Isobutene &$^1B_1 (\mathrm{R}; \pi \ra 3s)$ & 6.46 &6.46 &6.37 &6.54& 6.59 &6.46 &6.47 &6.45 &6.43 \\
&$^1A_1 (\mathrm{R}; \pi \ra 3p)$ & 7.01 &7.01 &6.95 &7.09& 7.11 &7.00 &7.01 &7.00 &6.97 \\
&$^3A_1 (\Val; (\pi \ra \pis)$ & 4.53 &4.68 &4.62 &4.48& 4.22 & & &4.53 &4.62 \\
Methylenecyclopropene& $^1B_2 (\Val; \pi \ra \pis)$ & 4.28 &4.72 &4.51 &4.58& 4.76 &4.35 &4.38 &4.31 &4.46 \\
&$^1B_1 (\mathrm{R}; \pi \ra 3s)$ & 5.44 &5.43 &5.35 &5.48& 5.45 &5.44 &5.45 &5.44 &5.38 \\
&$^1A_2 (\mathrm{R}; \pi \ra 3p)$ & 5.96 &5.94 &5.85 &6.00& 6.01 &5.96 &5.97 &5.95 &5.87 \\
&$^1A_1(\Val; \pi \ra \pis)$ & \emph{6.12} &6.14 &6.09 &6.18& 6.21 &6.12 &6.14 &6.13 &6.09 \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 3.49 &3.94 &3.64 &3.57& 3.67 & & &3.50 &3.61 \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 4.74 &4.86 &4.81 &4.69& 4.78 & & &4.74 &4.80 \\
Propynal & $^1A'' (\Val; n \ra \pis)$ & 3.80 &3.95 &3.96 &3.84& 3.82 &3.86 &3.85 &3.82 &3.78 \\
&$^1A'' (\Val; \pi \ra \pis)$ & 5.54 &5.95 &5.71 &5.69& 5.72 &5.57 &5.55 &5.51 &5.73 \\
&$^3A'' (\Val; n \ra \pis)$ & 3.47 &3.55 &3.53 &3.53& 3.40 & & &3.49 &3.38 \\
&$^3A' (\Val; \pi \ra \pis)$ & 4.47 &4.81 &4.71 &4.40& 4.38 & & &4.43 &4.67 \\
Pyrazine &$^1B_{3u} (\Val; n \ra \pis)$ & 4.15 &4.37 &4.14 &4.32& 4.10 &4.21 &4.20 &4.14 &4.17 \\
&$^1A_{u} (\Val; n \ra \pis)$ & 4.98 &4.91 &4.86 &5.23& 5.04 &5.04 &5.06 &4.97 &4.88 \\
&$^1B_{2u} (\Val; \pi \ra \pis)$ & 5.02 &5.26 &5.14 &5.15& 4.83 &5.09 &5.06 &5.03 &5.47 \\
&$^1B_{2g} (\Val; n \ra \pis)$ & 5.71 &6.22 &5.86 &6.00& 5.71 &5.84 &5.80 &5.71 &5.87 \\
&$^1A_{g} (\mathrm{R}; n \ra 3s)$ & 6.65 &6.20 &6.20 &6.83& 6.86 &6.71 &6.74 &6.66 &6.30 \\
&$^1B_{1g} (\Val; n \ra \pis)$ & 6.74 &7.31 &6.67 &7.14& 7.33 &6.85 &6.87 &6.73 &6.67 \\
&$^1B_{1u} (\Val; \pi \ra \pis)$ & 6.88 &7.13 &6.89 &6.96& &6.90 &6.88 &6.86 &6.88 \\
&$^1B_{1g} (\mathrm{R}; \pi \ra 3s)$ & 7.21 &7.31 &7.21 &7.26& &7.22 &7.21 &7.20 &7.27 \\
&$^1B_{2u} (\mathrm{R}; n \ra 3p)$ & 7.24 &7.30 &6.74 &7.44& 7.49 &7.31 &7.35 &7.25 & \\
&$^1B_{1u} (\mathrm{R}; n \ra 3p)$ & 7.44 &7.19 &7.03 &7.60& &7.50 &7.52 &7.45 & \\
&$^1B_{1u} (\Val; \pi \ra \pis)$ & \emph{7.98} &7.85 &7.87 &8.20& &7.98 &8.02 &7.94 & \\
&$^3B_{3u} (\Val; n \ra \pis)$ & 3.59 &3.84 &3.60 &3.70& 3.48 & & &3.59 &3.62 \\
&$^3B_{1u} (\Val; \pi \ra \pis)$ & 4.35 &4.76 &4.60 &4.19& 3.93 & & &4.39 &4.57 \\
&$^3B_{2u} (\Val; (\pi \ra \pis)$ & 4.39 &4.67 &4.57 &4.40& 4.32 & & &4.40 &4.59 \\
&$^3A_{u} (\Val; n \ra \pis)$ & 4.93 &4.93 &4.82 &5.16& 4.97 & & &4.93 &4.84 \\
&$^3B_{2g} (\Val; n \ra \pis)$ & 5.08 &5.41 &5.19 &5.21& 4.89 & & &5.08 & \\
&$^3B_{1u} (\Val; \pi \ra \pis)$ & 5.28 &5.59 &5.59 &5.35& 5.21 & & &5.29 & \\
Pyridazine &$^1B_1 (\Val; n \ra \pis)$ & 3.83 &4.12 &3.78 &4.03& 3.76 &3.91 &3.89 &3.83 &3.79 \\
&$^1A_2 (\Val; n \ra \pis)$ & 4.37 &4.84 &4.26 &4.65& 4.44 &4.46 &4.47 &4.37 &4.27 \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 5.26 &5.51 &5.43 &5.43& &5.36 &5.32 &5.29 &5.44 \\
&$^1A_2 (\Val; n \ra \pis)$ & 5.72 &5.62 &5.79 &6.01& 5.76 &5.84 &5.82 &5.74 &5.81 \\
&$^1B_2 (\mathrm{R}; n \ra 3s)$ & 6.17 &5.83 &5.59 &6.42& 6.45 &6.27 &6.31 &6.17 &5.69 \\
&$^1B_1 (\Val; n \ra \pis)$ & 6.37 &6.39 &6.33 &6.67& 6.47 &6.46 &6.47 &6.37 &6.35 \\
&$^1B_2 (\Val; \pi \ra \pis)$ & 6.75 & &6.86 &6.88& &6.81 &6.77 &6.74 &6.85 \\
&$^3B_1 (\Val; n \ra \pis)$ & 3.19 &3.50 &3.18 &3.30& 3.06 & & &3.19 &3.19 \\
&$^3A_2 (\Val; n \ra \pis)$ & 4.11 &4.64 &4.01 &4.31& 4.13 & & &4.11 &4.02 \\
&$^3B_2 (\Val; \pi \ra \pis)$ & \emph{4.34} &4.75 &4.61 &4.17& 3.89 & & &4.38 &4.60 \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 4.82 &5.18 &5.07 &4.86& 4.78 & & &4.83 &5.06 \\
Pyridine &$^1B_1 (\Val; n \ra \pis)$ & 4.95 &5.22 &4.99 &5.17& 4.94 &5.04 &5.03 &4.96 &4.98 \\
&$^1B_2 (\Val; \pi \ra \pis)$ & 5.14 &5.40 &5.32 &5.29& 5.03 &5.23 &5.20 &5.17 &5.33 \\
&$^1A_2 (\Val; n \ra \pis)$ & 5.40 &5.33 &5.28 &5.64& 5.45 &5.46 &5.48 &5.40 &5.27 \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 6.62 &6.84 &6.24 &6.96& 6.98 &6.67 &6.65 &6.63 &6.31 \\
&$^1A_1 (\mathrm{R}; n \ra 3s)$ & 6.76 &6.38 &6.68 &6.71& &6.83 &6.86 &6.76 &6.65 \\
&$^1A_2 (\mathrm{R}; \pi \ra 3s)$ & 6.82 &6.88 &6.79 &6.87& 6.94 &6.83 &6.83 &6.81 &6.83 \\
&$^1B_2 (\Val; \pi \ra \pis)$ & \emph{7.40} &7.56 &7.37 &7.55& &7.40 & &7.38 &6.87 \\
&$^1B_1 (\mathrm{R}; \pi \ra 3p)$ & 7.38 &7.42 &7.34 &7.43& 7.49 &7.40 &7.40 &7.38 &7.38 \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 7.39 &7.56 &7.45 &7.59& &7.44 &7.47 &7.39 &7.48 \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 4.30 &4.66 &4.53 &4.15& 3.93 & & &4.33 &4.53 \\
&$^3B_1 (\Val; n \ra \pis)$ & 4.46 &4.72 &4.48 &4.59& 4.41 & & &4.46 &4.47 \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 4.79 &5.08 &4.98 &4.83& 4.78 & & &4.79 &4.98 \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 5.04 &5.33 &5.29 &5.11& 5.03 & & &5.05 &5.28 \\
&$^3A_2 (\Val; n \ra \pis)$ & 5.36 &5.36 &5.24 &5.58& 5.39 & & &5.35 &5.23 \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 6.24 &6.40 &6.39 &6.26& 6.25 & & &6.25 &6.35 \\
Pyrimidine &$^1B_1 (\Val; n \ra \pis)$ & 4.44 &4.57 &4.41 &4.66& 4.36 &4.51 &4.51 &4.44 &4.37 \\
&$^1A_2 (\Val; n \ra \pis)$ & 4.85 &4.97 &4.77 &5.07& 4.81 &4.92 &4.94 &4.86 &4.73 \\
&$^1B_2 (\Val; \pi \ra \pis)$ & 5.38 &5.58 &5.54 &5.53& 5.15 &5.47 &5.44 &5.41 &5.52 \\
&$^1A_2 (\Val; n \ra \pis)$ & 5.92 &6.06 &5.96 &6.20& 5.91 &6.03 &6.02 &5.93 &5.93 \\
&$^1B_1 (\Val; n \ra \pis)$ & 6.26 &7.22 &6.25 &6.54& 6.26 &6.34 &6.36 &6.26 &6.22 \\
&$^1B_2 (\mathrm{R}; n \ra 3s)$ & 6.70 &6.23 &6.20 &6.88& 6.90 &6.77 &6.81 &6.72 &6.25 \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 6.88 &7.07 &6.84 &6.97& &6.91 &6.89 &6.87 &6.83 \\
&$^3B_1 (\Val; n \ra \pis)$ & 4.09 &4.31 &4.07 &4.25& 4.02 & & &4.10 &4.05 \\
&$^3A_1 (\Val; \pi \ra \pis)$ & \emph{4.51} &4.91 &4.77 &4.39& 4.11 & & &4.55 &4.76 \\
&$^3A_2 (\Val; n \ra \pis)$ & 4.66 &5.01 &4.60 &4.83& 4.63 & & &4.66 &4.58 \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 4.96 &5.23 &5.17 &4.99& 4.88 & & &4.96 &5.14 \\
Pyrrole &$^1A_2 (\mathrm{R}; \pi \ra 3s)$ & 5.24 &5.34 &5.23 &5.34& 5.36 &5.28 &5.26 &5.24 &5.30 \\
&$^1B_1 (\mathrm{R}; \pi \ra 3p)$ & 6.00 &6.04 &5.91 &6.04& 6.08 &6.01 &6.00 &5.98 &5.94 \\
&$^1A_2 (\mathrm{R}; \pi \ra 3p)$ & 6.00 &6.04 &5.96 &6.09& 6.15 &6.04 &6.03 &6.01 &6.03 \\
&$^1B_2 (\Val; (\pi \ra \pis)$ & 6.26 &6.62 &6.30 &6.35& 6.44 &6.28 &6.27 &6.25 &6.35 \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 6.30 &6.64 &6.47 &6.51& &6.39 &6.36 &6.32 &6.47 \\
&$^1B_2 (\mathrm{R}; \pi \ra 3p)$ & 6.83 &7.00 &6.89 &6.93& &6.85 &6.85 &6.83 &6.91 \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 4.51 &4.81 &4.72 &4.45& 4.15 & & &4.53 &4.71 \\
&$^3A_2 (\mathrm{R}; \pi \ra 3s)$ & 5.21 &5.33 &5.20 &5.30& 5.41 & & &5.21 &5.27 \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 5.45 &5.70 &5.66 &5.49& 5.12 & & &5.46 &5.62 \\
&$^3B_1 (\mathrm{R}; \pi \ra 3p)$ & 5.91 &6.01 &5.86 &5.97& 6.06 & & &5.92 &5.89 \\
Tetrazine &$^1B_{3u} (\Val; n \ra \pis)$ & 2.47 &2.67 &2.38 &2.64& 2.36 &2.54 &2.52 &2.46 &2.42 \\
&$^1A_{u} (\Val; n \ra \pis)$ & 3.69 &3.93 &3.53 &3.96& 3.73 &3.77 &3.78 &3.67 &3.58 \\
&$^1A_{g} (\Val; n,n \ra \pis, \pis)$ & \emph{4.61} & & & & & &6.77 &6.21 & \\
&$^1B_{1g} (\Val; n \ra \pis)$ & 4.93 &5.58 &5.02 &5.26& 4.90 &5.09 &5.03 &4.91 &5.04 \\
&$^1B_{2u} (\Val; \pi \ra \pis)$ & 5.21 &5.40 &5.31 &5.37& 4.92 &5.31 &5.26 &5.23 &5.31 \\
&$^1B_{2g} (\Val; n \ra \pis)$ & 5.45 &6.09 &5.64 &5.84& 5.49 &5.64 &5.57 &5.46 &5.68 \\
&$^1A_{u} (\Val; n \ra \pis)$ & 5.53 &5.64 &5.56 &5.77& 5.50 &5.63 & &5.52 &5.59 \\
&$^1B_{3g} (\Val; n,n \ra \pis, \pis)$ & \emph{6.15} & & & & & & &7.62 & \\
&$^1B_{2g} (\Val; n \ra \pis)$ & 6.12 &6.08 &6.18 &6.66& &6.34 &6.32 &6.13 &6.21 \\
&$^1B_{1g} (\Val; n \ra \pis)$ & 6.91 &6.39 &6.95 &7.32& &7.04 &7.05 &6.92 &6.97 \\
&$^3B_{3u} (\Val; n \ra \pis)$ & 1.85 &2.13 &1.81 &1.96& 1.70 & & &1.85 &1.85 \\
&$^3A_{u} (\Val; n \ra \pis)$ & 3.45 &4.00 &3.31 &3.66& 3.47 & & &3.44 &3.35 \\
&$^3B_{1g} (\Val; n \ra \pis)$ & 4.20 &4.46 &4.27 &4.31& 3.96 & & &4.20 &4.27 \\
&$^3B_{1u} (\Val; \pi \ra \pis)$ & \emph{4.49} &4.96 &4.81 &4.27& 3.90 & & &4.54 &4.80 \\
&$^3B_{2u} (\Val; \pi \ra \pis)$ & 4.52 &4.87 &4.77 &4.53& 4.43 & & &4.52 &4.76 \\
&$^3B_{2g} (\Val; n \ra \pis)$ & 5.04 &5.47 &5.15 &5.23& 4.91 & & &5.05 &5.16 \\
&$^3A_{u} (\Val; n \ra \pis)$ & 5.11 &5.74 &5.13 &5.28& 5.04 & & &5.11 &5.16 \\
&$^3B_{3g} (\Val; n,n \ra \pis, \pis)$ & \emph{5.51} & & & & & & &7.35 & \\
&$^3B_{1u} (\Val; \pi \ra \pis)$ & 5.42 &5.74 &5.70 &5.52& 5.43 & & &5.42 &5.67 \\
Thioacetone &$^1A_2 (\Val; n \ra \pis)$ & 2.53 &2.55 &2.63 &2.63& 2.47 &2.55 &2.57 &2.55 &2.47 \\
&$^1B_2 (\mathrm{R}; n \ra 4s)$ & 5.56 &5.59 &5.50 &5.67& 5.72 &5.57 &5.61 &5.55 &5.47 \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 5.88 &6.01 &6.09 &6.01& &5.90 &5.93 &5.90 &5.87 \\
&$^1B_2 (\mathrm{R}; n \ra 4p)$ & 6.51 &6.54 &6.53 &6.59& 6.62 &6.52 &6.54 &6.51 &6.43 \\
&$^1A_1 (\mathrm{R}; n \ra 4p)$ & 6.61 &6.52 &6.44 &6.71& 6.76 &6.62 &6.66 &6.61 &6.48 \\
&$^3A_2 (\Val; n \ra \pis)$ & 2.33 &2.30 &2.33 &2.35& 2.25 & & &2.34 &2.20 \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 3.45 &3.60 &3.59 &3.66& 3.22 & & &3.46 &3.52 \\
Thiophene &$^1A_1 (\Val; \pi \ra \pis)$ & 5.64 &5.77 &5.75 &5.78& &5.69 &5.69 &5.65 &5.72 \\
&$^1B_2 (\Val; \pi \ra \pis)$ & 5.98 &6.24 &6.07 &6.12& &6.00 &5.99 &5.96 &6.07 \\
&$^1A_2 (\mathrm{R}; \pi \ra 3s)$ & 6.14 &6.18 &6.07 &6.22& 6.18 &6.17 &6.15 &6.14 &6.15 \\
&$^1B_1 (\mathrm{R}; \pi \ra 3p)$ & 6.14 &6.44 &6.15 &6.31& 6.23 &6.20 &6.18 &6.14 &6.24 \\
&$^1A_2 (\mathrm{R}; \pi \ra 3p)$ & 6.21 &6.42 &6.35 &6.32& 6.16 &6.28 &6.28 &6.25 &6.35 \\
&$^1B_1 (\mathrm{R}; \pi \ra 3s)$ & 6.49 &6.49 &6.48 &6.56& 6.52 &6.52 &6.52 &6.50 &6.51 \\
&$^1B_2 (\mathrm{R}; \pi \ra 3p)$ & 7.29 &7.37 &7.26 &7.38& 7.35 &7.33 &7.31 &7.29 &7.34 \\
&$^1A_1 (\Val; \pi \ra \pis)$ & \emph{7.31} &7.68 &7.48 &7.57& &7.46 &7.42 &7.35 &7.51 \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 3.92 &4.22 &4.12 &3.85& 3.70 & & &3.94 &4.11 \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 4.76 &5.02 &4.91 &4.77& 4.71 & & &4.77 &4.86 \\
&$^3B_1 (\mathrm{R}; \pi \ra 3p)$ & 5.93 &6.28 &6.00 &6.12& 6.16 & & &5.95 &6.09 \\
&$^3A_2 (\mathrm{R}; \pi \ra 3s)$ & 6.08 &6.17 &6.03 &6.16& 6.24 & & &6.09 &6.11 \\
Thiopropynal &$^1A'' (\Val; n \ra \pis)$ & 2.03 &2.14 &2.20 &2.15& 2.06 &2.07 &2.08 &2.05 &2.08 \\
&$^3A'' (\Val; n \ra \pis)$ & 1.80 &1.83 &1.84 &1.83& 1.79 & & &1.81 &1.74 \\
Triazine &$^1A_1'' (\Val; n \ra \pis)$ & 4.72 &4.59 &4.64 &4.92& 4.62 &4.77 &4.80 &4.73 &4.58 \\
&$^1A_2'' (\Val; n \ra \pis)$ & 4.75 &4.86 &4.75 &4.99& 4.76 &4.82 &4.82 &4.74 &4.69 \\
&$^1E'' (\Val; n \ra \pis)$ & 4.78 &4.84 &4.72 &4.99& 4.74 &4.84 &4.86 &4.78 &4.66 \\
&$^1A_2' (\Val; \pi \ra \pis)$ & 5.75 &5.83 &5.89 &5.91& 5.45 &5.85 &5.82 &5.78 &5.83 \\
&$^1A_1' (\Val; \pi \ra \pis)$ & 7.24 &7.39 &7.32 &7.34& &7.28 &7.27 &7.24 &7.18 \\
&$^1E' (\mathrm{R}; n \ra 3s)$ & 7.32 &7.83 &6.87 &7.45& &7.37 &7.41 &7.35 &6.89 \\
&$^1E'' (\Val; n \ra \pis)$ & 7.78 & &7.71 &8.13& &7.96 & &7.79 & \\
&$^1E' (\Val; \pi \ra \pis)$ & 7.94 &7.84 &7.63 &8.14& &7.95 & &7.92 &7.65 \\
&$^3A_2'' (\Val; n \ra \pis)$ & 4.33 &4.52 &4.32 &4.51& 4.32 & & &4.33 &4.29 \\
&$^3E'' (\Val; n \ra \pis)$ & 4.51 &4.71 &4.46 &4.67& 4.47 & & &4.51 &4.42 \\
&$^3A_1'' (\Val; n \ra \pis)$ & 4.73 &4.65 &4.65 &4.91& 4.43 & & &4.75 &4.59 \\
&$^3A_1' (\Val; \pi \ra \pis)$ & 4.85 &5.27 &5.12 &4.74& 4.69 & & &4.88 &5.10 \\
&$^3E' (\Val; \pi \ra \pis)$ & 5.59 &5.91 &5.88 &5.70& 5.61 & & &5.61 &5.82 \\
&$^3A_2' (\Val; (\pi \ra \pis)$ & 6.62 &6.71 &6.76 &6.59& 6.60 & & &6.63 &6.63 \\
\end{longtable}
\end{footnotesize}
\end{landscape}
\clearpage
\subsection{Statistical analysis}
\begin{table}[htp]
\caption{MSE (in eV) obtained for various subsets of transition energies.}
\label{Table-SI-b2}
\begin{tabular}{lcccccc}
\hline
Method & Singlet & Triplet & Valence & Rydberg & $n\rightarrow\pi^\star$ & $\pi\rightarrow\pi^\star$ \\
\hline
CIS(D) &0.10 &0.24 &0.24 &-0.05 &0.19 &0.28 \\
{\AD} &-0.04 &0.07 &0.06 &-0.13 &-0.04 &0.14 \\
{\CCD} &-0.03 &0.10 &0.10 &-0.17 &0.01 &0.17 \\
{\STEOM} &0.06 &-0.06 &-0.04 &0.12 &-0.02 &-0.06 \\
{\CCSD} &0.15 &0.05 &0.12 &0.09 &0.19 &0.07 \\
CCSDR(3) &0.05 & &0.07 &0.02 &0.08 &0.06 \\
CCSDT-3 &0.05 & &0.06 &0.03 &0.08 &0.04 \\
{\CCT} &0.00 &0.01 &0.01 &0.00 &0.00 &0.01 \\
\hline
\end{tabular}
\end{table}
\clearpage
\section{Geometries}
Below, we provide the cartesian coordinates of the compounds investigated in this study.
These are provided in atomic units (bohr) and they have been obtained at the \CC{3}(full)/{\AVTZ} level of theory.
\subsection{Acetone}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 0.00000000 0.18807702
C 0.00000000 2.42007545 -1.31764698
C 0.00000000 -2.42007545 -1.31764698
O 0.00000000 0.00000000 2.48269094
H 0.00000000 4.03690733 -0.05185132
H 0.00000000 -4.03690733 -0.05185132
H 1.66061256 2.48420530 -2.53995285
H -1.66061256 2.48420530 -2.53995285
H 1.66061256 -2.48420530 -2.53995285
H -1.66061256 -2.48420530 -2.53995285
\end{verbatim}
\end{singlespace}
\subsection{Acrolein}
\begin{singlespace}
\begin{verbatim}
C -1.11645072 -0.68348783 0.00000000
C 1.20647847 0.83714564 0.00000000
C 3.46831059 -0.28872636 0.00000000
O -3.23666415 0.19187203 0.00000000
H -0.80613858 -2.74747338 0.00000000
H 0.98699813 2.86613511 0.00000000
H 5.20930864 0.77443560 0.00000000
H 3.60951559 -2.33000749 0.00000000
\end{verbatim}
\end{singlespace}
\clearpage
\subsection{Benzene}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 2.63144965 0.00000000
C -2.27890225 1.31572483 0.00000000
C -2.27890225 -1.31572483 0.00000000
C 0.00000000 -2.63144965 0.00000000
C 2.27890225 -1.31572483 0.00000000
C 2.27890225 1.31572483 0.00000000
H -4.04725813 2.33668557 0.00000000
H -4.04725813 -2.33668557 0.00000000
H -0.00000000 -4.67337115 0.00000000
H 4.04725813 -2.33668557 0.00000000
H 4.04725813 2.33668557 0.00000000
H 0.00000000 4.67337115 0.00000000
\end{verbatim}
\end{singlespace}
\subsection{Butadiene}
\begin{singlespace}
\begin{verbatim}
C 1.14656244 0.00000000 0.75468820
C -1.14656244 0.00000000 -0.75468820
C 3.48132647 0.00000000 -0.22482805
C -3.48132647 0.00000000 0.22482805
H 0.90770978 0.00000000 2.78883925
H -0.90770978 0.00000000 -2.78883925
H 3.77525814 0.00000000 -2.24895470
H -3.77525814 0.00000000 2.24895470
H 5.13664967 0.00000000 0.96861890
H -5.13664967 0.00000000 -0.96861890
\end{verbatim}
\end{singlespace}
\subsection{Cyanoacetylene}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 0.00000000 -3.59120182
C 0.00000000 0.00000000 -1.30693904
C 0.00000000 0.00000000 1.28880240
N 0.00000000 0.00000000 3.48692211
H 0.00000000 0.00000000 -5.59619886
\end{verbatim}
\end{singlespace}
\clearpage
\begin{singlespace}
\noindent Lowest excited state
\begin{verbatim}
C 1.99411175 0.00000000 2.81781077
C -0.07304269 0.00000000 1.33125774
C -0.63630126 0.00000000 -1.14556678
N -1.39755756 0.00000000 -3.26154643
H 1.90749857 0.00000000 4.87279180
\end{verbatim}
\end{singlespace}
\subsection{Cyanoformaldehyde}
\begin{singlespace}
\begin{verbatim}
C -0.91561483 0.00000000 -1.22522833
C -0.01092219 0.00000000 1.39523175
N 0.64170259 0.00000000 3.48820325
O 0.50833684 0.00000000 -3.00337867
H -2.97202213 0.00000000 -1.42565674
\end{verbatim}
\end{singlespace}
\subsection{Cyanogen}
\begin{singlespace}
Ground state
\begin{verbatim}
C 0.00000000 0.00000000 1.30401924
C 0.00000000 0.00000000 -1.30401924
N 0.00000000 0.00000000 3.49784121
N 0.00000000 0.00000000 -3.49784121
\end{verbatim}
\end{singlespace}
\begin{singlespace}
\noindent Lowest excited state
\begin{verbatim}
C 0.00000000 0.00000000 1.22784115
C 0.00000000 0.00000000 -1.22784115
N 0.00000000 0.00000000 3.56462559
N 0.00000000 0.00000000 -3.56462559
\end{verbatim}
\end{singlespace}
\clearpage
\subsection{Cyclopentadiene}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 0.00000000 -2.33113051
C 0.00000000 2.22209092 -0.56871188
C 0.00000000 -2.22209092 -0.56871188
C 0.00000000 1.38514451 1.83772922
C 0.00000000 -1.38514451 1.83772922
H 1.66130504 0.00000000 -3.56414299
H -1.66130504 0.00000000 -3.56414299
H 0.00000000 4.16550405 -1.18116624
H 0.00000000 -4.16550405 -1.18116624
H 0.00000000 2.54514584 3.51352303
H 0.00000000 -2.54514584 3.51352303
\end{verbatim}
\end{singlespace}
\subsection{Cyclopropenone}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 1.27491826 -1.86930519
C 0.00000000 -1.27491826 -1.86930519
C 0.00000000 0.00000000 0.51814554
O 0.00000000 0.00000000 2.79326776
H 0.00000000 2.92791371 -3.05679837
H 0.00000000 -2.92791371 -3.05679837
\end{verbatim}
\end{singlespace}
\subsection{Cyclopropenethione}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 1.26230744 -2.86571925
C 0.00000000 -1.26230744 -2.86571925
C 0.00000000 0.00000000 -0.49233236
S 0.00000000 0.00000000 2.57821680
H 0.00000000 2.97773331 -3.95114059
H 0.00000000 -2.97773331 -3.95114059
\end{verbatim}
\end{singlespace}
\clearpage
\subsection{Diacetylene}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 0.00000000 1.29447700
C 0.00000000 0.00000000 -1.29447700
C 0.00000000 0.00000000 3.58448429
C 0.00000000 0.00000000 -3.58448429
H 0.00000000 0.00000000 5.58943003
H 0.00000000 0.00000000 -5.58943003
\end{verbatim}
\end{singlespace}
\subsection{Furan}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 2.06365826 -0.60051250
C 0.00000000 -2.06365826 -0.60051250
C 0.00000000 1.35348578 1.86336416
C 0.00000000 -1.35348578 1.86336416
O 0.00000000 0.00000000 -2.13945332
H 0.00000000 3.86337287 -1.53765695
H 0.00000000 -3.86337287 -1.53765695
H 0.00000000 2.59168789 3.47168051
H 0.00000000 -2.59168789 3.47168051
\end{verbatim}
\end{singlespace}
\subsection{Glyoxal}
\begin{singlespace}
\begin{verbatim}
C 1.21360282 0.75840215 0.00000000
C -1.21360282 -0.75840215 0.00000000
O 3.25581408 -0.26453186 0.00000000
O -3.25581408 0.26453186 0.00000000
H 0.96135276 2.81883243 0.00000000
H -0.96135276 -2.81883243 0.00000000
\end{verbatim}
\end{singlespace}
\clearpage
\subsection{Imidazole}
\begin{singlespace}
\begin{verbatim}
C 0.41662795 2.06006259 0.00000000
C -1.52618386 -1.62343163 0.00000000
C 1.04160471 -1.93007427 0.00000000
N -1.90345764 0.94914956 0.00000000
N 2.24215443 0.38083431 0.00000000
H 0.65501634 4.07748278 0.00000000
H -3.57500545 1.84103166 0.00000000
H -3.06363894 -2.94559167 0.00000000
H 2.08673940 -3.67001102 0.00000000
\end{verbatim}
\end{singlespace}
\subsection{Isobutene}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 0.00000000 2.70790758
C 0.00000000 0.00000000 0.18431282
C 0.00000000 2.39894572 -1.32482735
C 0.00000000 -2.39894572 -1.32482735
H 0.00000000 1.74848405 3.76691310
H 0.00000000 -1.74848405 3.76691310
H 0.00000000 4.05897160 -0.10582007
H 0.00000000 -4.05897160 -0.10582007
H 1.66026992 2.48337908 -2.55086178
H -1.66026992 2.48337908 -2.55086178
H 1.66026992 -2.48337908 -2.55086178
H -1.66026992 -2.48337908 -2.55086178
\end{verbatim}
\end{singlespace}
\subsection{Methylenecyclopropene}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 0.00000000 0.53512883
C 0.00000000 0.00000000 3.04739824
C 0.00000000 1.25042956 -1.88571561
C 0.00000000 -1.25042956 -1.88571561
H 0.00000000 2.96887531 -2.96270271
H 0.00000000 -2.96887531 -2.96270271
H 0.00000000 1.75335023 4.08608382
H 0.00000000 -1.75335023 4.08608382
\end{verbatim}
\end{singlespace}
\subsection{Propynal}
\begin{singlespace}
\begin{verbatim}
C -0.78051115 0.00000000 -1.38900384
C -0.17873562 0.00000000 1.27825868
C 0.23763714 0.00000000 3.52644798
O 0.80143996 0.00000000 -3.04628328
H -2.80713069 0.00000000 -1.82768750
H 0.64026209 0.00000000 5.48853193
\end{verbatim}
\end{singlespace}
\subsection{Pyrazine}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 2.13188686 1.31510863
C 0.00000000 -2.13188686 1.31510863
C 0.00000000 2.13188686 -1.31510863
C 0.00000000 -2.13188686 -1.31510863
N 0.00000000 0.00000000 2.66620111
N 0.00000000 0.00000000 -2.66620111
H 0.00000000 3.88751412 2.35234226
H 0.00000000 -3.88751412 2.35234226
H 0.00000000 3.88751412 -2.35234226
H 0.00000000 -3.88751412 -2.35234226
\end{verbatim}
\end{singlespace}
\subsection{Pyridazine}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 1.30150855 -2.31552865
C 0.00000000 -1.30150855 -2.31552865
C 0.00000000 2.49271907 0.03513416
C 0.00000000 -2.49271907 0.03513416
N 0.00000000 1.26228251 2.23104685
N 0.00000000 -1.26228251 2.23104685
H 0.00000000 4.52804172 0.19299731
H 0.00000000 -4.52804172 0.19299731
H 0.00000000 2.39011496 -4.03967703
H 0.00000000 -2.39011496 -4.03967703
\end{verbatim}
\end{singlespace}
\subsection{Pyridine}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 0.00000000 -2.66451139
C 0.00000000 2.25494985 -1.32069889
C 0.00000000 -2.25494985 -1.32069889
C 0.00000000 2.15398594 1.30669632
C 0.00000000 -2.15398594 1.30669632
N 0.00000000 0.00000000 2.62778932
H 0.00000000 0.00000000 -4.70641516
H 0.00000000 4.05768507 -2.27625442
H 0.00000000 -4.05768507 -2.27625442
H 0.00000000 3.88059079 2.40341581
H 0.00000000 -3.88059079 2.40341581
\end{verbatim}
\end{singlespace}
\subsection{Pyrimidine}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 0.00000000 2.41518350
C 0.00000000 -0.00000000 -2.60410885
C 0.00000000 2.23272561 -1.22869402
C 0.00000000 -2.23272561 -1.22869402
N 0.00000000 2.26214196 1.29619742
N 0.00000000 -2.26214196 1.29619742
H 0.00000000 0.00000000 4.45780256
H 0.00000000 0.00000000 -4.64120942
H 0.00000000 4.05149341 -2.16351748
H 0.00000000 -4.05149341 -2.16351748
\end{verbatim}
\end{singlespace}
\subsection{Pyrrole}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 2.11924634 0.62676569
C 0.00000000 -2.11924634 0.62676569
C 0.00000000 1.34568862 -1.85506908
C 0.00000000 -1.34568862 -1.85506908
N 0.00000000 0.00000000 2.10934391
H 0.00000000 0.00000000 4.00257355
H 0.00000000 3.97648410 1.44830201
H 0.00000000 -3.97648410 1.44830201
H 0.00000000 2.56726559 -3.47837232
H 0.00000000 -2.56726559 -3.47837232
\end{verbatim}
\end{singlespace}
\subsection{Tetrazine}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 0.00000000 2.38208164
C 0.00000000 0.00000000 -2.38208164
N 2.25673244 0.00000000 1.24973261
N -2.25673244 0.00000000 1.24973261
N 2.25673244 0.00000000 -1.24973261
N -2.25673244 0.00000000 -1.24973261
H 0.00000000 0.00000000 4.41850901
H 0.00000000 0.00000000 -4.41850901
\end{verbatim}
\end{singlespace}
\subsection{Thioacetone}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 0.00000000 0.68476030
C 0.00000000 2.38541696 2.20685096
C 0.00000000 -2.38541696 2.20685096
S 0.00000000 0.00000000 -2.39920303
H 0.00000000 4.04609254 1.00090614
H 0.00000000 -4.04609254 1.00090614
H 1.65894780 2.42602225 3.43712000
H -1.65894780 2.42602225 3.43712000
H 1.65894780 -2.42602225 3.43712000
H -1.65894780 -2.42602225 3.43712000
\end{verbatim}
\end{singlespace}
\subsection{Thiophene}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 2.33342542 -0.09858421
C 0.00000000 -2.33342542 -0.09858421
C 0.00000000 1.34371718 -2.48297725
C 0.00000000 -1.34371718 -2.48297725
S 0.00000000 0.00000000 2.17250692
H 0.00000000 4.29028016 0.44577296
H 0.00000000 -4.29028016 0.44577296
H 0.00000000 2.48760051 -4.16768392
H 0.00000000 -2.48760051 -4.16768392
\end{verbatim}
\end{singlespace}
\subsection{Thiopropynal}
\begin{singlespace}
\begin{verbatim}
C -0.00382924 0.00000000 -1.25249909
C -2.27832423 0.00000000 0.15152736
C -4.26309583 0.00000000 1.29548793
S 2.81920288 0.00000000 -0.00828974
H -0.23056990 0.00000000 -3.28862183
H -5.97712967 0.00000000 2.33206931
\end{verbatim}
\end{singlespace}
\subsection{Triazine}
\begin{singlespace}
\begin{verbatim}
C 0.00000000 -2.11414732 -1.22060353
C 0.00000000 0.00000000 2.44120705
C 0.00000000 2.11414732 -1.22060353
N 0.00000000 -2.24624733 1.29687150
N 0.00000000 2.24624733 1.29687150
N 0.00000000 0.00000000 -2.59374300
H 0.00000000 3.88296710 -2.24183210
H 0.00000000 -3.88296710 -2.24183210
H 0.00000000 0.00000000 4.48366420
\end{verbatim}
\end{singlespace}
\clearpage
\end{document}