done with 4 atoms

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Pierre-Francois Loos 2019-11-10 23:16:03 +01:00
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@ -595,37 +595,36 @@ $^i${0-0 energies from Ref.~\citenum{Jud84c}.}
\end{table}
\titou{HERE}
For acetone, one should clearly distinguish the valence ES, for which both methodological and basis set effects are small, and the Rydberg transitions that, not only are very
sensitive to the basis set, but are upshifted by ca.~$0.04$ eV with {\CCSDTQ} as compared to {\CCT} and {\CCSDT}. For this compound, the 1996 {\CASPT} transition energies of Merch\'an and coworkers listed on the
r.h.s. of Table \ref{Table-4} are quite clearly too small, especially for the three valence ES. \cite{Mer96b} As expected, this error can be partially ascribed to the details of the calculations, as the Urban group obtained {\CASPT}
excitation energies of $4.40$, $4.09$ and $6.22$ eV for the $^1A_2$, $^3A_2$, and $^3A_1$ ES, \cite{Pas12} in much better agreement with ours. Their estimates for the three $n \ra 3p$ transitions of $7.52$, $7.57$, and $7.53$ eV
for the $^1A_2$, $^1A_1$, and $^1B_2$ ES also systematically fall within $0.10$ eV of our current CC values, whereas for these three ES, the current {\NEV} values are quite clearly too large.
For acetone, one should clearly distinguish the valence ES, for which both methodological and basis set effects are small, and the Rydberg transitions that both very
sensitive to the basis set, and upshifted by ca.~$0.04$ eV with {\CCSDTQ} as compared to {\CCT} and {\CCSDT}. For this compound, the 1996 {\CASPT} transition energies of Merch\'an and coworkers listed on the
right panel of Table \ref{Table-4} are clearly too low, especially for the three valence ES. \cite{Mer96b} As expected, this error can be partially ascribed to the \titou{details of the calculations}, as the Urban group obtained {\CASPT}
excitation energies of $4.40$, $4.09$ and $6.22$ eV for the $^1A_2$, $^3A_2$, and $^3A_1$ ES, \cite{Pas12} in much better agreement with ours. Their estimates of the three $n \ra 3p$ transitions, $7.52$, $7.57$, and $7.53$ eV
for the $^1A_2$, $^1A_1$, and $^1B_2$ ES, also systematically fall within $0.10$ eV of our current CC values, whereas for these three ES, the current {\NEV} values are clearly too large.
In contrast to acetone, both valence and Rydberg ES of thioacetone are rather insensitive to the CC expansion, as illustrated by the maximal discrepancies of $\pm$0.02 eV between the {\CCT} and {\CCSDTQ} results
with the {\Pop} basis set. While the lowest $n \ra \pis$ transition of both spin symmetries are rather insensitive to the selected basis set, all other states need quite large bases to be correctly described (Table S4).
As expected our theoretical vertical transition energies show the same ranking but are systematically larger than the available experimental 0-0 energies.
In contrast to acetone, both valence and Rydberg ES of thioacetone are rather insensitive to the CC expansion, as illustrated by the maximal discrepancies of $\pm$0.02 eV between the {\CCT}/{\Pop} and {\CCSDTQ}/{\Pop} results.
While the lowest $n \ra \pis$ transition of both spin symmetries are rather basis set insensitive, all the other states need quite large one-electron bases to be correctly described (Table S4).
As expected, our theoretical vertical transition energies show the same ranking but are systematically larger than the available experimental 0-0 energies.
For the isoleectronic isobutene, we considered two singlet Rydberg and one triplet valence ES. For all three cases, we note very nice agreement between {\CCT} and {\CCSDT} results for all considered basis sets, the
CC results being also within or very close to the {\FCI} estimates with Pople's basis set. The match with the {\CCSD} results of Caricato and coworkers, \cite{Car10} is also very satisfying.
For the isoleectronic isobutene molecule, we have considered two singlet Rydberg state and one triplet valence ES. For these three cases, we note, for each basis, a very nice agreement between {\CCT} and {\CCSDT}, the
CC results being also very close to the {\FCI} estimates obtained with the Pople basis set. The similarity with the {\CCSD} results of Caricato and coworkers \cite{Car10} is also very satisfying.
For the three remaining compounds, namely, cyanoformaldehyde, propynal, and thiopropynal, we report low-lying valence transitions all showing a largely dominant single excitation character. The basis set
For the three remaining compounds, namely, cyanoformaldehyde, propynal, and thiopropynal, we report low-lying valence transitions with a definite single excitation character. The basis set
effects are clearly under control (they are only significant for the second $^1A''$ ES of cyanoformaldehyde) and we could not detect any variation larger than $0.03$ eV between the {\CCT} and {\CCSDT} values for
a given basis, hinting that the CC values should be close to the spot, as confirmed by the {\FCI} data.
a given basis, alluding that the CC values are very accurate.
This is further confirmed by the {\FCI} data.
\subsubsection{Intermediate conclusions}
\label{sec-ic}
As we have seen for the 15 four-atom molecules considered here, we found extremely consistent transition energies between the tested CC approaches and the {\FCI} estimates in the vast majority of cases,
Importantly, we confirm the previous conclusions obtained on smaller compounds:\cite{Loo18a} i) {\CCSDTQ} values systematically fall within, or are extremely close from, the {\FCI} error bar,
ii) both {\CCT} and {\CCSDT} are also highly trustable when the considered ES does not show a very strong double excitation character. Indeed, considering all the 54 ``single transitions''
for which {\CCSDTQ} estimates could be obtained (only excluding the lowest $^1A_g$ ES of butadiene and glyoxal), we determined trifling mean signed errors (MSE of 0.00 eV), tiny
As we have seen for the 15 four-atom molecules considered here, we found extremely consistent transition energies between CC and {\FCI} estimates in the vast majority of the cases.
Importantly, we confirm our previous conclusions obtained on smaller compounds: \cite{Loo18a} i) {\CCSDTQ} values systematically fall within (or are extremely close to) the {\FCI} error bar,
ii) both {\CCT} and {\CCSDT} are also highly trustable when the considered ES does not exhibit a strong double excitation character. Indeed, considering the 54 ``single'' excitations
for which {\CCSDTQ} estimates could be obtained (only excluding the lowest $^1A_g$ ES of butadiene and glyoxal), we determined negligible mean signed errors (MSE of $0.00$ eV), tiny
MAE ($0.01$ and $0.02$ eV), and small maximal deviations ($0.05$ and $0.04$ eV) for {\CCT} and {\CCSDT}, respectively. This clearly indicates that these two approaches provide chemically-accurate
estimates (errors $< 1$ kcal.mol$^{-1}$ or $0.043$ eV) for most electronic transitions. Interestingly, some of us have shown that {\CCT} also provides chemically-accurate 0-0 energies as compared
to experimental values for most valence transitions. \cite{Loo18b,Loo19a,Sue19} When comparing the {\NEV} and {\CCT} ({\CCSDT}) results obtained with {\AVTZ} for all transitions in four-atom molecules,
one obtains a mean signed deviation of $+0.09$ ($+0.09$) eV and a mean absolute deviation of $0.11$ ($0.12$) eV, considering all 91 (65) ES for which comparisons are possible, again excluding only
the lowest $^1A_g$ states of butadiene and glyoxal. Although the error cannot be fully ascribed to the multi-reference method, that is additionally dependent of the selected active space, it seems to
indicate that {\NEV}, as applied here, has a slight tendency to overestimate the transition energies. This contrasts with the {\CASPT} approach that, from the comparisons discussed above,
generally undershoots the transition energies.
estimates (errors below $1$ kcal.mol$^{-1}$ or $0.043$ eV) for most electronic transitions. Interestingly, some of us have shown that {\CCT} also provides chemically-accurate 0-0 energies as compared
to experimental values for most valence transitions. \cite{Loo18b,Loo19a,Sue19} When comparing the {\NEV} and {\CCT} ({\CCSDT}) results obtained with {\AVTZ} for the 91 (65) ES for which comparisons are possible (again excluding only the lowest $^1A_g$ states of butadiene and glyoxal),
one obtains a mean signed deviation of $+0.09$ ($+0.09$) eV and a mean absolute deviation of $0.11$ ($0.12$) eV.
This seems to indicate that {\NEV}, as applied here, has a slight tendency to overestimate the transition energies. This contrasts with {\CASPT} that is known to generally underestimate transition energies, as further illustrated and discussed above.
\subsection{Five-atom molecules}
@ -688,7 +687,7 @@ $^c${MR-CC results from Ref.~\citenum{Li10c};}
$^d${{\AT} results from Ref.~\citenum{Hol15};}
$^e${{\CCT} results from Ref.~\citenum{Sch17};}
$^f${Various experiments summarized in Ref.~\citenum{Wan00};}
$^g${Electron impact from Ref.~\citenum{Vee76b}: for the $^1A_1$ state two values (6.44 and 6.61 eV) are reported, whereas for the two lowest triplet states, 3.99 eV and 5.22 eV values can be found in Ref.~\citenum{Fli76};}
$^g${Electron impact from Ref.~\citenum{Vee76b}: for the $^1A_1$ state two values (6.44 and 6.61 eV) are reported, whereas for the two lowest triplet states, Two values (3.99 eV and 5.22 eV) can be found in Ref.~\citenum{Fli76};}
$^h${{\NEV} results from Ref.~\citenum{Pas06c};}
$^i${Best estimate from Ref.~\citenum{Chr99}, based on CC calculations;}
$^j${XMS-{\CASPT} results from Ref.~\citenum{Hei19};}
@ -768,7 +767,7 @@ $^c${MR-MP results from Ref.~\citenum{Nak96};}
$^d${{\CCT} results from Ref.~\citenum{Sch17};}
$^e${Electron impact from Ref.~\citenum{Fru79};}
$^f${Gas phase absorption from Ref.~\citenum{McD91b};}
$^g${Energy loss from Ref.~\citenum{McD85} for the two valence state; two-photon resonant experiment from Ref.~\citenum{Sab92} for the $^1A_2$ Rydberg ES;}
$^g${Energy loss from Ref.~\citenum{McD85} for the two valence states; two-photon resonant experiment from Ref.~\citenum{Sab92} for the $^1A_2$ Rydberg ES;}
$^h${{\CASPT} results from Ref.~\citenum{Ser96b};}
$^i${{\CCT} results from Ref.~\citenum{Sil10c};}
$^j${Gas-phase experimental estimates from Ref.~\citenum{Dev06};}
@ -777,7 +776,7 @@ $^l${SAC-CI results from Ref.~\citenum{Wan01};}
$^m${CCSDR(3) results from Ref.~\citenum{Pas07};}%, this work also contains {\NEV} estimates;}
$^n${TBE from Ref.~\citenum{Hol14}, based on EOM-CCSD for singlet and ADC(2) for triplets;}
$^o${0-0 energies from Ref.~\citenum{Dil72};}
$^p${0-0 energies from Ref.~\citenum{Var82} for the singlets and energy loss experiment from Ref.~\citenum{Hab03} for the triplet ES;}
$^p${0-0 energies from Ref.~\citenum{Var82} for the singlets and energy loss experiment from Ref.~\citenum{Hab03} for the triplets;}
$^q${0-0 energies from Ref.~\citenum{Hol14}.}
\end{footnotesize}
\end{flushleft}
@ -854,7 +853,7 @@ $^b${{\CCT} results from Ref.~\citenum{Chr96c};}
$^c${SAC-CI results from Ref.~\citenum{Li07b};}
$^d${RASPT2(18,18) results from Ref.~\citenum{Sha19};}
$^e${Electron impact from Ref.~\citenum{Doe69};}
$^f${Jet-cooled experiment from Ref.~\citenum{Hir91} for the two lowest states, multi-photon experiments from Refs.~ \citenum{Joh76} and \citenum{Joh83} for the Rydberg states.}
$^f${Jet-cooled experiment from Ref.~\citenum{Hir91} for the two lowest states, multi-photon experiments from Refs.~\citenum{Joh76} and \citenum{Joh83} for the Rydberg states.}
\end{footnotesize}
\end{flushleft}
\end{table}
@ -922,14 +921,14 @@ $^a${{\CASPT} results from Ref.~\citenum{Web99};}
$^b${{\STEOM} results from Ref.~\citenum{Noo99};}
$^c${SAC-CI results from Ref.~\citenum{Li07b};}
$^d${{\CCT} results from Ref.~\citenum{Sch17};}
$^e${Dip spectroscopy from Ref.~\citenum{Oku90} ($B_{3u}$ and $B_{2g}$ states) and EEL from Ref.~\citenum{Wal91} (other states);}
$^e${\titou{Dip} spectroscopy from Ref.~\citenum{Oku90} ($B_{3u}$ and $B_{2g}$ states) and EEL from Ref.~\citenum{Wal91} (other states);}
$^f${UV max from Ref.~\citenum{Bol84};}
$^g${{\CASPT} results from Ref.~\citenum{Rub99};}
$^h${Ext-{\STEOM} results from Ref.~\citenum{Noo00};}
$^i${GVVPT2 results from Ref.~\citenum{Dev08};}
$^j${{\NEV} results from Ref.~\citenum{Ang09};}
$^k${{\CCT} results from Ref.~\citenum{Sil10c};}
$^l${From Ref.~\citenum{Pal97}, the singlets are from EEL, but for the 4.97 and 5.92 eV values that are from VUV; the triplets are from EEL, and other triplet peaks are mentioned at 4.21, 4.6, and 5.2 eV but not identified;}
$^l${From Ref.~\citenum{Pal97}, the singlets are from EEL, except for the $4.97$ and $5.92$ eV values that are from VUV; the triplets are from EEL, and other triplet peaks are mentioned at $4.21$, $4.6$, and $5.2$ eV but not identified;}
$^m${all these doubly ES have a $(n,n \ra \pis, \pis)$ character.}
\end{footnotesize}
\end{flushleft}
@ -1089,7 +1088,7 @@ $^d${EOM-CCSD({$\tilde{{T}}$}) from Ref.~\citenum{Del97b};}
$^e${UV max from Ref.~\citenum{Bol84};}
$^f${EEL from Ref.~\citenum{Lin15};}
$^g${{\CASPT} from Ref.~\citenum{Oli05};}
$^h${CC3-ext. from Ref.~\citenum{Sil10c}.}
$^h${CC3-ext.~from Ref.~\citenum{Sil10c}.}
\end{footnotesize}
\end{flushleft}
\end{table}
@ -1381,12 +1380,12 @@ Triazine &$^1A_1'' (\Val; n \ra \pis)$ & & 88.3 & 4.72 & {\CCSDT}/AVTZ
\begin{flushleft}\begin{footnotesize}\begin{singlespace}
\vspace{-0.6 cm}
$^a${
Method A: {\CCSDT}/{\AVTZ} value corrected by the difference between {\CCSDTQ}/{\AVDZ} and {\CCSDT}/{\AVDZ} results;
Method B: {\CCSDT}/{\AVTZ} value corrected by the difference between {\CCSDTQ}/{\Pop} and {\CCSDT}/{\Pop} results;
Method C: {\CCT}/{\AVTZ} value corrected by the difference between {\CCSDTQ}/{\Pop} and {\CCT}/{\Pop} results;
Method D: {\CCT}/{\AVTZ} value corrected by the difference between {\CCSDT}/{\AVDZ} and {\CCT}/{\AVDZ} results;
Method E: {\CCT}/{\AVTZ} value corrected by the difference between {\CCSDT}/{\Pop} and {\CCT}/{\Pop} results;
Method F: {exCI}/{\AVDZ} value (from Ref.~\citenum{Loo19c}) corrected by the difference between {\CCSDT}/{\AVTZ} and {\CCSDT}/{\AVDZ} results.
Method A: {\CCSDT}/{\AVTZ} value corrected by the difference between {\CCSDTQ}/{\AVDZ} and {\CCSDT}/{\AVDZ};
Method B: {\CCSDT}/{\AVTZ} value corrected by the difference between {\CCSDTQ}/{\Pop} and {\CCSDT}/{\Pop};
Method C: {\CCT}/{\AVTZ} value corrected by the difference between {\CCSDTQ}/{\Pop} and {\CCT}/{\Pop};
Method D: {\CCT}/{\AVTZ} value corrected by the difference between {\CCSDT}/{\AVDZ} and {\CCT}/{\AVDZ};
Method E: {\CCT}/{\AVTZ} value corrected by the difference between {\CCSDT}/{\Pop} and {\CCT}/{\Pop};
Method F: {\FCI}/{\AVDZ} value (from Ref.~\citenum{Loo19c}) corrected by the difference between {\CCSDT}/{\AVTZ} and {\CCSDT}/{\AVDZ}.
}
\end{singlespace}\end{footnotesize}\end{flushleft}