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\documentclass[journal=jctcce,manuscript=article,layout=traditional]{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}}
\newcommand{\mc}{\multicolumn}
\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}
\newcommand{\STEOM}{STEOM-CCSD}
\newcommand{\AT}{ADC(3)}
\newcommand{\CC}[1]{CC#1}
\newcommand{\CCSD}{CCSD}
\newcommand{\EOMCCSD}{EOM-CCSD}
\newcommand{\CCSDT}{CCSDT}
\newcommand{\CCSDTQ}{CCSDTQ}
\newcommand{\CI}{CI}
\newcommand{\sCI}{sCI}
\newcommand{\exCI}{exFCI}
\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}
\newcommand{\AVQZ}{\emph{aug}-cc-pVQZ}
\newcommand{\DAVQZ}{d-\emph{aug}-cc-pVQZ}
\newcommand{\TAVQZ}{t-\emph{aug}-cc-pVQZ}
\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}}
\newcommand{\Fl}{\mathrm{F}}
\newcommand{\ra}{\rightarrow}
\newcommand{\SI}{Supporting Information}
\setcounter{table}{0}
\setcounter{figure}{0}
\setcounter{page}{1}
\setcounter{equation}{0}
\renewcommand{\thepage}{S\arabic{page}}
\renewcommand{\thefigure}{S\arabic{figure}}
\renewcommand{\theequation}{S\arabic{equation}}
\renewcommand{\thetable}{S\arabic{table}}
\renewcommand{\thesection}{S\arabic{section}}
\renewcommand\floatpagefraction{.99}
\renewcommand\topfraction{.99}
\renewcommand\bottomfraction{.99}
\renewcommand\textfraction{.01}
% 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{Highly-Accurate Reference Excitation Energies and Benchmarks: 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
\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 $\pis$ orbitals.
$^b$Using reference (6e,9o) active space including valence $\pis$ and three $3p_z$ orbitals.
$^c$Using reference (6e,7o) active space including valence $\pis$ and 3s orbitals.
$^d$Using reference (6e,8o) active space including valence $\pis$, $3p_x$ 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 \\
\hline
Cyanoacetylene &$^1\Sigma^- (\Val; \pi \ra \pis)$ & \\
&$^1\Delta (\Val; \pi \ra \pis)$ & \\
&$^3\Sigma^+ (\Val; \pi \ra \pis)$ & \\
&$^3\Delta (\Val; \pi \ra \pis)$ & \\
&$^1A'' [\mathrm{F}] (\Val; \pi \ra \pis)$ & \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
\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 \\
\hline
Cyanogen & $^1\Sigma_u^- (\Val; \pi \ra \pis)$ & \\
& $^1\Delta_u (\Val; \pi \ra \pis)$ & \\
& $^3\Sigma_u^+ (\Val; \pi \ra \pis)$ & \\
& $^1\Sigma_u^- [\mathrm{F}] (\Val; \pi \ra \pis)$ & \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
\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$^c$ \\
&$^1A_1 (\Val; \pi \ra \pis)$ &6.75$^{a,f}$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ &3.41$^a$ \\
&$^3A_1 (\Val; \pi \ra \pis)$ &5.36$^a$ \\
&$^3A_2 (\Ryd; \pi \ra 3s)$ &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 \\
\hline
Cyclopropenone &$^1B_1 (\Val; n \ra \pis)$ & 4.04$^a$,4.20$^b$,4.21$^c$ \\
&$^1A_2 (\Val; n \ra \pis)$ & 5.85$^a$,5.86$^b$,5.94$^c$ \\
&$^1B_2 (\Ryd; n \ra 3s)$ & 6.51$^a$,6.64$^b$,6.75$^c$ \\
&$^1B_2 (\Val; \pi \ra \pis$) & 6.82$^a$,6.93$^b$,7.06$^c$ \\
&$^1B_2 (\Ryd; n \ra 3p)$ & 7.07$^a$,7.25$^b$,7.38$^c$ \\
&$^1A_1 (\Ryd; n \ra 3p)$ & 7.28$^a$,7.08$^b$,7.28$^c$ \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 8.19$^a$,8.19$^c$ \\
&$^3B_1 (\Val; n \ra \pis)$ & 3.51$^a$,3.68$^b$,3.67$^c$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 5.10$^a$,5.09$^b$,5.29$^c$ \\
&$^3A_2 (\Val; n \ra \pis)$ & 5.60$^a$,5.60$^b$,5.69$^c$ \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 7.16$^a$,7.21$^b$,7.16$^c$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$Using reference (6e,7o) active space averaging with the ground state for each irreducible representation.
$^b$Using reference (6e,7o) active space averaging between three states of the same irreducible representation.
$^c$Using reference (6e,7o) active space averaging between four states of the same 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 \\
\hline
Diacetylene &$^1\Sigma_u^- (\Val; \pi \ra \pis)$ & \\
&$^1\Delta_u (\Val; \pi \ra \pis)$ & \\
&$^3\Sigma_u^+ (\Val; \pi \ra \pis)$ & \\
&$^3\Delta_u (\Val; \pi \ra \pis)$ & \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
\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 nO, $\si_\text{CC}$, $\si_\text{CO}$, $\si^*_\text{CC}$ and $\si^*_\text{CO}$ orbitals.
$^b$Using reference (14e,13o) active space including valence $\pi$, two nO, $\si_\text{CC}$, $\si_\text{CO}$, $\si^*_\text{CC}$, $\si^*_\text{CO}$ and $3p_z$ orbitals.
$^c$Non-negligible doubly-excited and Rydberg character.
$^d$Using reference (14e,13o) active space including valence $\pi$, two nO, $\si_\text{CC}$, $\si_\text{CO}$, $\si^*_\text{CC}$, $\si^*_\text{CO}$ 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$^c$ \\
&$^1A_1(\Val; \pi \ra \pis)$ &7.55$^d$,7.95$^e$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ &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.
$^f$The $\pi^*$ orbital has some diffuse character, even in the case of natural orbitals.
$^g$Heavily mixed states.
\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$^a$ \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 5.58b \\
&$^1A_2 (\Val; n \ra \pis)$ & 5.88$^a$ \\
&$^1B_2 (\Ryd; n \ra 3s)$ & 6.21c \\
&$^1B_1 (\Val; n \ra \pis)$ & 6.64$^a$ \\
&$^1B_2 (\Val; \pi \ra \pis)$ & 7.82b,7.19d,7.10e \\
&$^3B_1 (\Val; n \ra \pis)$ & 3.13$^a$ \\
&$^3A_2 (\Val; n \ra \pis)$ & 4.14$^a$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 4.65b,4.55d,4.49e \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 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$^a$,5.15b \\
&$^1B_2 (\Val; \pi \ra \pis)$ & 5.44c,5.31d \\
&$^1A_2 (\Val; n \ra \pis)$ & 5.32$^a$,5.29e \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 6.69c \\
&$^1A_1 (\Ryd; n \ra 3s)$ & 6.99e \\
&$^1A_2 (\Ryd; \pi \ra 3s)$ & 6.96f,6.86e\\
&$^1B_2 (\Val; \pi \ra \pis)$ & 8.61$^a$,7.83d \\
&$^1B_1 (\Ryd; \pi \ra 3p)$ & 7.57g,7.45b \\
&$^1A_1 (\Val; \pi \ra \pis)$ & 6.97c \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 4.60c \\
&$^3B_1 (\Val; n \ra \pis)$ & 4.58$^a$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 4.90c,4.88d \\
&$^3A_1 (\Val; \pi \ra \pis)$ & 5.19c \\
&$^3A_2 (\Val; n \ra \pis)$ & 5.33$^a$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 7.00c,6.29d \\
\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$^e$ \\
&$^3B_2 (\Val; \pi \ra \pis)$ & 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$^f$ \\
&$^1B_2 (\Ryd; \pi \ra 3p)$ & 77.42$^b$,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 \\
\hline
Thiopropynal &$^1A'' (\Val; n \ra \pis)$ & 2.05$^a$ \\
&$^3A'' (\Val; n \ra \pis)$ & 1.81$^a$ \\
\hline
\end{tabularx}
\begin{flushleft}
\begin{footnotesize}
$^a$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$^v$,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}
\end{document}