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% energies
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% energies
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\newcommand{\EFCI}{E_\text{FCI}}
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\newcommand{\EFCI}{E_\text{FCI}}
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\newcommand{\EexCI}{E_\text{exCI}}
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\newcommand{\EexCI}{E_\text{exCI}}
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\newcommand{\EsCI}{E_\text{sCI}}
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\newcommand{\ESCI}{E_\text{SCI}}
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\newcommand{\EPT}{E_\text{PT2}}
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\newcommand{\EPT}{E_\text{PT2}}
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\newcommand{\PsisCI}{\Psi_\text{sCI}}
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\newcommand{\PsiSCI}{\Psi_\text{SCI}}
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\newcommand{\Ndet}{N_\text{det}}
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\newcommand{\Ndet}{N_\text{det}}
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\newcommand{\ex}[6]{$^{#1}#2_{#3}^{#4}(#5 \ra #6)$}
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\newcommand{\ex}[6]{$^{#1}#2_{#3}^{#4}(#5 \ra #6)$}
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@ -44,7 +44,7 @@
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\newcommand{\CCSDTQ}{CCSDTQ}
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\newcommand{\CCSDTQ}{CCSDTQ}
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\newcommand{\CCSDTQP}{CCSDTQP}
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\newcommand{\CCSDTQP}{CCSDTQP}
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\newcommand{\CI}{CI}
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\newcommand{\CI}{CI}
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\newcommand{\sCI}{sCI}
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\newcommand{\SCI}{SCI}
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\newcommand{\exCI}{exCI}
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\newcommand{\exCI}{exCI}
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\newcommand{\FCI}{FCI}
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\newcommand{\FCI}{FCI}
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Following our previous work focussing on compounds containing up to 3 non-hydrogen atoms [\emph{J. Chem. Theory Comput.} {\bfseries 14} (2018) 4360--4379], we present here highly-accurate vertical transition energies
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Following our previous work focussing on compounds containing up to 3 non-hydrogen atoms [\emph{J. Chem. Theory Comput.} {\bfseries 14} (2018) 4360--4379], we present here highly-accurate vertical transition energies
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obtained for 27 molecules encompassing 4, 5, and 6 non-hydrogen atoms: acetone, acrolein, benzene, butadiene, cyanoacetylene, cyanoformaldehyde, cyanogen, cyclopentadiene, cyclopropenone, cyclopropenethione,
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obtained for 27 molecules encompassing 4, 5, and 6 non-hydrogen atoms: acetone, acrolein, benzene, butadiene, cyanoacetylene, cyanoformaldehyde, cyanogen, cyclopentadiene, cyclopropenone, cyclopropenethione,
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diacetylene, furan, glyoxal, imidazole, isobutene, methylenecyclopropene, propynal, pyrazine, pyridazine, pyridine, pyrimidine, pyrrole, tetrazine, thioacetone, thiophene, thiopropynal, and triazine.
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diacetylene, furan, glyoxal, imidazole, isobutene, methylenecyclopropene, propynal, pyrazine, pyridazine, pyridine, pyrimidine, pyrrole, tetrazine, thioacetone, thiophene, thiopropynal, and triazine.
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To obtain these energies, we use equation-of-motion coupled cluster theory up to the highest technically possible excitation order for these systems ({\CCT}, {\CCSDT}, and {\CCSDTQ}), selected configuration interaction ({\sCI}) calculations (with tens of millions of determinants in the reference space),
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To obtain these energies, we use equation-of-motion coupled cluster theory up to the highest technically possible excitation order for these systems ({\CCT}, {\CCSDT}, and {\CCSDTQ}), selected configuration interaction ({\SCI}) calculations (with tens of millions of determinants in the reference space),
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as well as the multiconfigurational $n$-electron valence state perturbation theory (NEVPT2) method.
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as well as the multiconfigurational $n$-electron valence state perturbation theory (NEVPT2) method.
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All these approaches are applied in combination with diffuse-containing atomic basis sets. For all transitions, we report at least {\CCT}/{\AVQZ} vertical excitation
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All these approaches are applied in combination with diffuse-containing atomic basis sets. For all transitions, we report at least {\CCT}/{\AVQZ} vertical excitation
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energies as well as {\CCT}/{\AVTZ} oscillator strengths for each dipole-allowed transition. We show that {\CCT} almost systematically delivers transition energies in agreement with higher-level theoretical methods with a typically deviation of $\pm 0.04$ eV, except for transitions with a dominant double excitation character where the error is much larger.
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energies as well as {\CCT}/{\AVTZ} oscillator strengths for each dipole-allowed transition. We show that {\CCT} almost systematically delivers transition energies in agreement with higher-level theoretical methods with a typically deviation of $\pm 0.04$ eV, except for transitions with a dominant double excitation character where the error is much larger.
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@ -125,7 +125,9 @@ one is typically limited to the use of time-dependent density-functional theory
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choose an ``appropriate'' exchange-correlation functional, which is difficult yet primordial as the impact of the exchange-correlation functional is exacerbated within TD-DFT as compared to DFT. \cite{Lau13} Such selection can, of course, rely
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choose an ``appropriate'' exchange-correlation functional, which is difficult yet primordial as the impact of the exchange-correlation functional is exacerbated within TD-DFT as compared to DFT. \cite{Lau13} Such selection can, of course, rely
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on the intrinsic features of the various exchange-correlation functional families, \eg, it is well-known that range-separated hybrids provide a more physically-sound description of long-range charge-transfer transitions than semi-local exchange-correlation functionals. \cite{Dre04,Pea08}
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on the intrinsic features of the various exchange-correlation functional families, \eg, it is well-known that range-separated hybrids provide a more physically-sound description of long-range charge-transfer transitions than semi-local exchange-correlation functionals. \cite{Dre04,Pea08}
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However, to obtain a quantitative assessment of the accuracy that can be expected from TD-DFT calculations, benchmarks cannot be avoided. This is why so many assessments of TD-DFT performances for various properties are
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However, to obtain a quantitative assessment of the accuracy that can be expected from TD-DFT calculations, benchmarks cannot be avoided. This is why so many assessments of TD-DFT performances for various properties are
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available. \cite{Lau13} While several of these benchmarks rely on experimental data as reference (typically band shapes \cite{Die04,Die04b,Avi13,Cha13,Lat15b,Mun15,Vaz15,San16b} or 0-0 energies
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available. \cite{Lau13}
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While several of these benchmarks rely on experimental data as reference (typically band shapes \cite{Die04,Die04b,Avi13,Cha13,Lat15b,Mun15,Vaz15,San16b} or 0-0 energies
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\cite{Die04b,Goe10a,Jac12d,Chi13b,Win13,Fan14b,Jac14a,Jac15b,Loo19b}), reference from theoretical best estimates (TBE) based on state-of-the-art computational methods \cite{Sch08,Sau09,Sil10b,Sil10c,Sch17,Loo18a}
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\cite{Die04b,Goe10a,Jac12d,Chi13b,Win13,Fan14b,Jac14a,Jac15b,Loo19b}), reference from theoretical best estimates (TBE) based on state-of-the-art computational methods \cite{Sch08,Sau09,Sil10b,Sil10c,Sch17,Loo18a}
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is advantageous as it allows comparisons on a perfectly equal footing (same geometry, vertical transitions, no environmental effects, etc). In such a case, the challenge is in fact to obtain accurate TBE, as these top-notch theoretical models
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is advantageous as it allows comparisons on a perfectly equal footing (same geometry, vertical transitions, no environmental effects, etc). In such a case, the challenge is in fact to obtain accurate TBE, as these top-notch theoretical models
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generally come with a dreadful scaling with system size and, in addition, typically require large atomic basis sets to deliver transition energies close to the complete basis set (CBS) limit.
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generally come with a dreadful scaling with system size and, in addition, typically require large atomic basis sets to deliver transition energies close to the complete basis set (CBS) limit.
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@ -138,22 +140,28 @@ However, beyond comparisons with experiments, which are always challenging when
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Nowadays, it is common knowledge that CASPT2 has the tendency of underestimating vertical excitation energies in organic molecules.
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Nowadays, it is common knowledge that CASPT2 has the tendency of underestimating vertical excitation energies in organic molecules.
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A decade ago, Thiel and coworkers defined TBE for 104 singlet and 63 triplet valence ES in 28 small and medium conjugated CNOH organic molecules. \cite{Sch08,Sil10b,Sil10c} These TBE
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A decade ago, Thiel and coworkers defined TBE for 104 singlet and 63 triplet valence ES in 28 small and medium conjugated CNOH organic molecules. \cite{Sch08,Sil10b,Sil10c} These TBE
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were computed on MP2/6-31G(d) structures with several levels of theories, notably {\CASPT} and various coupled cluster (CC) variants ({\CCD}, {\CCSD}, and {\CCT}). Interestingly, while the default reference approach used by Thiel and coworkers to define his
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were computed on MP2/6-31G(d) structures with several levels of theories, notably {\CASPT} and various coupled cluster (CC) variants ({\CCD}, {\CCSD}, and {\CCT}). Interestingly, while the default theoretical protocol used by Thiel and coworkers to define their
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first series of TBE was {\CASPT}, \cite{Sch08} the majority of the most recent TBE (so-called ``TBE-2'' in Ref.~\citenum{Sil10c}) were determined at the {\CCT}/{\AVTZ} level, often using a basis set extrapolation technique.
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first series of TBE used {\CASPT}, \cite{Sch08} the vast majority of their most recent TBE (the so-called ``TBE-2'' in Ref.~\citenum{Sil10c}) were determined at the {\CCT}/{\AVTZ} level of theory, often using a basis set extrapolation technique.
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In more details, CC3/TZVP values were typically corrected for basis set effects by the difference between {\CCD}/{\AVTZ} and {\CCD}/TZVP results. \cite{Sil10b,Sil10c} Many works used Thiel's TBE for
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More specifically, CC3/TZVP values were corrected for basis set incompleteness errors by the difference between {\CCD}/{\AVTZ} and {\CCD}/TZVP results. \cite{Sil10b,Sil10c} Many works exploited Thiel's TBE for
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assessing low-order methods, \cite{Sil08,Goe09,Jac09c,Roh09,Sau09,Jac10c,Jac10g,Sil10,Mar11,Jac11a,Hui11,Del11,Tra11,Pev12,Dom13,Dem13,Sch13b,Voi14,Har14,Yan14b,Sau15,Pie15,Taj16,Mai16,Ris17,Dut18,Hel19} highlighting
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assessing low-order methods, \cite{Sil08,Goe09,Jac09c,Roh09,Sau09,Jac10c,Jac10g,Sil10,Mar11,Jac11a,Hui11,Del11,Tra11,Pev12,Dom13,Dem13,Sch13b,Voi14,Har14,Yan14b,Sau15,Pie15,Taj16,Mai16,Ris17,Dut18,Hel19} highlighting further
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their value for the community. In contrast, the number of extensions of this original set remains quite limited, \ie, {\CCSDT}/TZVP reference energies computed for 17 singlet states of six molecules appeared in 2014, \cite{Kan14}
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their value for the electronic structure community. In contrast, the number of extensions/improvements of this original set remains quite limited.
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and 46 {\CCSDT}/{\AVTZ} transition energies in small compounds containing two or three non-hydrogen atoms (ethylene, acetylene, formaldehyde, formaldimine, and formamide) have been described in 2017. \cite{Kan17}
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For example, K\'ann\'ar and Szalay computed, in 2014, {\CCSDT}/TZVP reference energies for 17 singlet states of six molecules. \cite{Kan14}
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This has motivated us to propose two years ago a set of 106 transition energies for which it was technically possible to reach the Full Configuration Interaction (FCI) limit by performing high-order CC calculations (up to {\CCSDTQP}) and selected
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Three years later, the same authors reported 46 {\CCSDT}/{\AVTZ} transition energies in small compounds containing two or three non-hydrogen atoms (ethylene, acetylene, formaldehyde, formaldimine, and formamide). \cite{Kan17}
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CI (sCI) transition energy calculations on {\CCT} GS structures. \cite{Loo18a} We used these TBE to benchmark many ES theories. \cite{Loo18a} Amongst our conclusions, we found that {\CCSDTQ} was on the {\FCI} spot, whereas we could not
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detect significant differences of accuracies between {\CCT} and {\CCSDT}, both being very accurate with mean absolute errors (MAE) as small as 0.03 eV compared to {\FCI} for ES with a single excitation character. These conclusions
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Following the same philosophy, two years ago, we reported a set of 106 transition energies for which it was technically possible to reach the full configuration interaction (FCI) limit by performing high-order CC (up to {\CCSDTQP}) and selected
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agree well with earlier studies. \cite{Wat13,Kan14,Kan17} We also recently proposed a set of 20 TBE for transitions presenting a large double excitation character. \cite{Loo19c} For such transitions, one can distinguish the ES
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CI (SCI) calculations on {\CCT}/{\AVTZ} GS structures. \cite{Loo18a} We exploited these TBE to benchmark many ES theories. \cite{Loo18a} Amongst our conclusions, we found that {\CCSDTQ} yields near-{\FCI} quality excitation energies, whereas we could not
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as a function of $\%T_1$, the percentage of single excitation calculated at the {\CCT} level. For ES with a significant yet not dominant double excitation character, such as the famous $A_g$ ES of butadiene ($\%T_1 = 75\%$),
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detect any significant differences between {\CCT} and {\CCSDT} transition energies, both being very accurate with mean absolute errors (MAE) as small as $0.03$ eV compared to {\FCI}.
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CC methods including triples in the GS treatment deliver rather accurate estimates (MAE of $0.11$ eV with {\CCT} and $0.06$ eV with {\CCSDT}), surprisingly outperforming second-order multi-reference schemes such as {\CASPT} or
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the generally robust $N$-Electron Valence State Perturbation Theory ({\NEV}). In contrast, for ES with a dominant double excitation character, \eg, the low-lying $n,n \ra \pis,\pis$ excitation in nitrosomethane ($\%T_1$=2\%),
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Although these conclusions agree well with earlier studies, \cite{Wat13,Kan14,Kan17} they obviously only hold for single excitations, \ie, transitions with $\%T_1$ in the range $90$--$100\%$. Therefore, we also recently proposed a set of 20 TBE for transitions exhibiting a significant double-excitation character (\ie, with $\%T_1$ typically below $80\%$). \cite{Loo19c}
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single-reference methods are not suited (MAE of $0.86$ eV with {\CCT} and $0.42$ eV with {\CCSDT}) and multi-reference methods are, in practice, required to obtain accurate results. \cite{Loo19c} Obviously, a clear limit of our 2018 work\cite{Loo18a}
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Unsurprisingly, our results clearly evidenced that the error in CC methods is intimately related to the $\%T_1$ value.
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is that we treated only compounds containing 1--3 non-hydrogen atoms, hence introducing a significant chemical bias. Therefore we have decided to go for larger molecules and we consider in the present contribution organic
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For example, ES with a significant yet \titou{not dominant} double excitation character, such as the infamous $A_g$ ES of butadiene ($\%T_1 = 75\%$),
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compounds encompassing 4, 5, and 6 non-hydrogen atoms. For such systems, performing {\CCSDTQ} calculations with large bases remains a dream, and, the convergence of {\sCI} with the number of determinants is slower
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CC methods including triples deliver rather accurate estimates (MAE of $0.11$ eV with {\CCT} and $0.06$ eV with {\CCSDT}), surprisingly outperforming second-order multi-reference schemes such as {\CASPT} or
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the generally robust $n$-electron valence state perturbation theory ({\NEV}). In contrast, for ES with a dominant double excitation character, \eg, the low-lying $(n,n) \ra (\pis,\pis)$ excitation in nitrosomethane ($\%T_1 = 2\%$),
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single-reference methods have been found to be unsuitable with MAEs of $0.86$ and $0.42$ eV for {\CCT} and {\CCSDT}, respectively.
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In this case, multireference methods are required to obtain accurate results. \cite{Loo19c}
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Obviously, a clear limit of our 2018 work\cite{Loo18a} is that we treated only compounds containing 1--3 non-hydrogen atoms, hence introducing a significant chemical bias. Therefore we have decided to go for larger molecules and we consider in the present contribution organic
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compounds encompassing 4, 5, and 6 non-hydrogen atoms. For such systems, performing {\CCSDTQ} calculations with large bases remains a dream, and, the convergence of {\SCI} with the number of determinants is slower
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as well, so that extrapolating to the {\FCI} limit with a ca.~$0.01$ eV error bar is rarely doable in practice. Consequently, the ``brute-force'' determination of {\FCI}/CBS estimates, as in our earlier work,\cite{Loo18a} is beyond reach.
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as well, so that extrapolating to the {\FCI} limit with a ca.~$0.01$ eV error bar is rarely doable in practice. Consequently, the ``brute-force'' determination of {\FCI}/CBS estimates, as in our earlier work,\cite{Loo18a} is beyond reach.
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Anticipating this problem, we have previously demonstrated that one can very accurately estimate such limit by correcting values obtained with a high-level of theory and a double-$\zeta$ basis set by {\CCT} results obtained with a
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Anticipating this problem, we have previously demonstrated that one can very accurately estimate such limit by correcting values obtained with a high-level of theory and a double-$\zeta$ basis set by {\CCT} results obtained with a
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larger basis, \cite{Loo18a} and we glibally follow such strategy here. In addition, we also performed {\NEV} calculations in an effort to check the consistency of our estimates, especially for ES with intermediate $\%T_1$ values.
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larger basis, \cite{Loo18a} and we glibally follow such strategy here. In addition, we also performed {\NEV} calculations in an effort to check the consistency of our estimates, especially for ES with intermediate $\%T_1$ values.
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@ -180,21 +188,21 @@ Several structures have been extracted from previous contributions, \cite{Bud17,
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\subsection{Selected Configuration Interaction methods}
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\subsection{Selected Configuration Interaction methods}
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All the sCI calculations have been performed in the frozen-core approximation with the latest version of QUANTUM PACKAGE \cite{Gar19} using the Configuration Interaction using a Perturbative Selection made Iteratively (CIPSI) algorithm to select the
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All the SCI calculations have been performed in the frozen-core approximation with the latest version of QUANTUM PACKAGE \cite{Gar19} using the Configuration Interaction using a Perturbative Selection made Iteratively (CIPSI) algorithm to select the
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most important determinants in the FCI space. Instead of generating all possible excited determinants like a conventional CI calculation, the iterative CIPSI algorithm performs a sparse exploration of the FCI space via a selection of the most relevant
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most important determinants in the FCI space. Instead of generating all possible excited determinants like a conventional CI calculation, the iterative CIPSI algorithm performs a sparse exploration of the FCI space via a selection of the most relevant
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determinants using a second-order perturbative criterion. At each iteration, the variational (or reference) space is enlarged with new determinants. CIPSI can be seen as a deterministic version of the FCIQMC algorithm developed by Alavi and
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determinants using a second-order perturbative criterion. At each iteration, the variational (or reference) space is enlarged with new determinants. CIPSI can be seen as a deterministic version of the FCIQMC algorithm developed by Alavi and
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coworkers. \cite{Boo09} We refer the interested reader to Ref.~\citenum{Gar19} where our implementation of the CIPSI algorithm is detailed.
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coworkers. \cite{Boo09} We refer the interested reader to Ref.~\citenum{Gar19} where our implementation of the CIPSI algorithm is detailed.
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Excited-state calculations are performed within a state-averaged formalism which means that the CIPSI algorithm select determinants simultaneously for the GS and ES. Therefore, all electronic states share the same set of determinants with different CI coefficients.
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Excited-state calculations are performed within a state-averaged formalism which means that the CIPSI algorithm select determinants simultaneously for the GS and ES. Therefore, all electronic states share the same set of determinants with different CI coefficients.
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Our implementation of the CIPSI algorithm for ES is detailed in Ref.~\citenum{Sce19}. For each system, a preliminary sCI calculation is performed using Hartree-Fock orbitals in order to generate sCI wavefunctions with at least 5,000,000 determinants.
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Our implementation of the CIPSI algorithm for ES is detailed in Ref.~\citenum{Sce19}. For each system, a preliminary SCI calculation is performed using Hartree-Fock orbitals in order to generate SCI wavefunctions with at least 5,000,000 determinants.
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State-averaged natural orbitals are then computed based on this wavefunction, and a new, larger sCI calculation is performed with this new set of orbitals. This has the advantage to produce a smoother and faster convergence of the sCI energy to the FCI limit.
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State-averaged natural orbitals are then computed based on this wavefunction, and a new, larger SCI calculation is performed with this new set of orbitals. This has the advantage to produce a smoother and faster convergence of the SCI energy to the FCI limit.
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For the largest systems, an additional iteration is sometimes required in order to obtain better quality natural orbitals and hence well-converged calculations.
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For the largest systems, an additional iteration is sometimes required in order to obtain better quality natural orbitals and hence well-converged calculations.
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The total sCI energy is defined as the sum of the (zeroth-order) variational energy (computed via diagonalization of the CI matrix in the reference space) and a second-order perturbative correction which takes into account the external determinants, \ie,
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The total SCI energy is defined as the sum of the (zeroth-order) variational energy (computed via diagonalization of the CI matrix in the reference space) and a second-order perturbative correction which takes into account the external determinants, \ie,
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the determinants which do not belong to the variational space but are linked to the reference space via a non-zero matrix element. The magnitude of this second-order correction, $E^{(2)}$, provides a qualitative idea of the ``distance" to the FCI limit.
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the determinants which do not belong to the variational space but are linked to the reference space via a non-zero matrix element. The magnitude of this second-order correction, $E^{(2)}$, provides a qualitative idea of the ``distance" to the FCI limit.
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For maximum efficiency, the total sCI energy is linearly extrapolated to $E^{(2)} = 0$ (which effectively corresponds to the FCI limit) using the two largest sCI wavefunctions. These extrapolated total energies simply (labeled as FCI in the remaining of the paper)
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For maximum efficiency, the total SCI energy is linearly extrapolated to $E^{(2)} = 0$ (which effectively corresponds to the FCI limit) using the two largest SCI wavefunctions. These extrapolated total energies simply (labeled as FCI in the remaining of the paper)
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are then used to computed vertical excitation energies. Although it is not possible to provide a theoretically-sound error bar, we estimate the extrapolation error by the difference in excitation energy between the largest sCI wavefunction and its corresponding
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are then used to computed vertical excitation energies. Although it is not possible to provide a theoretically-sound error bar, we estimate the extrapolation error by the difference in excitation energy between the largest SCI wavefunction and its corresponding
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extrapolated value. We believe that it provides a very safe estimate of the extrapolation error. Additional information about the sCI wavefunctions and excitation energies as well as their extrapolated values can be found in the SI.
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extrapolated value. We believe that it provides a very safe estimate of the extrapolation error. Additional information about the SCI wavefunctions and excitation energies as well as their extrapolated values can be found in the SI.
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\subsection{NEVPT2}
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\subsection{NEVPT2}
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\label{sec-res}
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\label{sec-res}
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In the following, we present the results obtained for molecules containing four, five, and six (non-hydrogen) atoms. In all cases, we test several atomic basis sets and push the CC excitation order as high as technically possible.
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In the following, we present the results obtained for molecules containing four, five, and six (non-hydrogen) atoms. In all cases, we test several atomic basis sets and push the CC excitation order as high as technically possible.
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Given that the {\sCI} results converges rather slowly for these larger systems, we provide an estimated error bar for these extrapolated {\FCI} values (\emph{vide supra}). In most cases, these extrapolated FCI reference data are used as a safety net to demonstrate the
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Given that the {\SCI} results converges rather slowly for these larger systems, we provide an estimated error bar for these extrapolated {\FCI} values (\emph{vide supra}). In most cases, these extrapolated FCI reference data are used as a safety net to demonstrate the
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consistency of the approaches rather than as definitive TBE (see next Section). We also show the results of {\NEV}/{\AVTZ} calculations for all relevant states to have a further consistency check. We underline that, except
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consistency of the approaches rather than as definitive TBE (see next Section). We also show the results of {\NEV}/{\AVTZ} calculations for all relevant states to have a further consistency check. We underline that, except
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when specifically discussed, all ES present a dominant single-excitation character (see also next Section), so that we do not expect serious CC breakdowns. This is especially true for the triplet ES that are known to show
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when specifically discussed, all ES present a dominant single-excitation character (see also next Section), so that we do not expect serious CC breakdowns. This is especially true for the triplet ES that are known to show
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very large \%$T_1$ for the vast majority of states, \cite{Sch08} and we consequently put our maximal computational effort on determining accurate transition energies for singlet states. To assign the different ES, we use literature data, as well as
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very large \%$T_1$ for the vast majority of states, \cite{Sch08} and we consequently put our maximal computational effort on determining accurate transition energies for singlet states. To assign the different ES, we use literature data, as well as
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Paraphrasing Thiel and coworkers, \cite{Sch08} we hope that this new set of vertical transition energies, combined or not with the ones described in our previous works, \cite{Loo18a,Loo19c} will be useful for the community,
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Paraphrasing Thiel and coworkers, \cite{Sch08} we hope that this new set of vertical transition energies, combined or not with the ones described in our previous works, \cite{Loo18a,Loo19c} will be useful for the community,
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will stimulate further developments and analyses in the field, and will provide new grounds for appraising the \emph{pros} and \emph{cons} of ES models already available or currently under development. We can
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will stimulate further developments and analyses in the field, and will provide new grounds for appraising the \emph{pros} and \emph{cons} of ES models already available or currently under development. We can
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crystal-ball that the emergence of new {\sCI} algorithms optimized for modern computer architectures will likely lead to the revision of some the present TBE, allowing to climb even higher on the accuracy ladder.
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crystal-ball that the emergence of new {\SCI} algorithms optimized for modern computer architectures will likely lead to the revision of some the present TBE, allowing to climb even higher on the accuracy ladder.
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\begin{suppinfo}
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\begin{suppinfo}
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Geometries.
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Geometries.
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Basis set and frozen core effects.
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Basis set and frozen core effects.
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Definition of the active spaces for the multi-reference calculations.
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Definition of the active spaces for the multi-reference calculations.
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Additional details about the {\sCI} calculations and their extrapolation.
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Additional details about the {\SCI} calculations and their extrapolation.
|
||||||
Benchmark data and further statistical analysis.
|
Benchmark data and further statistical analysis.
|
||||||
\end{suppinfo}
|
\end{suppinfo}
|
||||||
|
|
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Loading…
Reference in New Issue
Block a user