results section

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Pierre-Francois Loos 2019-04-13 18:53:02 +02:00
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However, from the quadruple-$\zeta$ basis, the LDA and PBE functionals agree within a few tenths of a {\kcal}. However, from the quadruple-$\zeta$ basis, the LDA and PBE functionals agree within a few tenths of a {\kcal}.
Such weak sensitivity to the approximated functionals in the DFT part when reaching large basis sets shows the robustness of the approach. Such weak sensitivity to the approximated functionals in the DFT part when reaching large basis sets shows the robustness of the approach.
We have computed the correlation energies of the G2-1 test sets with $\modY=\CCSDT$, $\modZ=\HF$ and the cc-pVXZ basis. We have computed the correlation energies of the G2-1 test sets with $\modY=\CCSDT$, $\modZ=\HF$ and the cc-pVXZ basis sets.
The plain CCSD(T) correlation energies as well as the corrected CCSD(T)+LDA and CCSD(T)+PBE values are reported. The ``plain'' CCSD(T) correlation energies as well as the corrected CCSD(T)+LDA and CCSD(T)+PBE values are depicted in Fig.~\ref{fig:G2_Ec}.
A statistical analysis of these data is also provided in Table \ref{tab:stats}, where one can find the mean absolute deviation (MAD), the root-mean-square deviation (RMSD), and the maximum deviation (MAX) with respect to the CCSD(T)/CBS reference correlation energies. The raw data can be found in the {\SI}.
A statistical analysis of these data is also provided in Table \ref{tab:stats}, where we have reported the mean absolute deviation (MAD), root-mean-square deviation (RMSD), and maximum deviation (MAX) with respect to the CCSD(T)/CBS correlation energies.
From double-$\zeta$ to quintuple-$\zeta$ basis, the MAD associated with the CCSD(T) correlation energies goes down slowly from 14.29 to 1.28 {\kcal}. From double-$\zeta$ to quintuple-$\zeta$ basis, the MAD associated with the CCSD(T) correlation energies goes down slowly from 14.29 to 1.28 {\kcal}.
For typical basis like cc-pVTZ, the MAD of CCSD(T) is still 6.06 {\kcal}. For a commonly-used basis like cc-pVTZ, the MAD of CCSD(T) is still 6.06 {\kcal}.
Applying the basis set correction drastically reduces the basis set incompleteness error. Applying the basis set correction drastically reduces the basis set incompleteness error.
Already at the CCSD(T)+LDA/cc-pVDZ and CCSD(T)+PBE/cc-pVDZ levels, the MAD is reduced to 3.24 and 1.96 {\kcal}. Already at the CCSD(T)+LDA/cc-pVDZ and CCSD(T)+PBE/cc-pVDZ levels, the MAD is reduced to 3.24 and 1.96 {\kcal}.
With the triple-$\zeta$ basis, the CCSD(T)+PBE/cc-pVTZ are already below 1 {\kcal} with 36 cases (out of 55) where we achieve chemical accuracy. With the triple-$\zeta$ basis, the MAD of CCSD(T)+PBE/cc-pVTZ is already below 1 {\kcal} with 36 cases (out of 55) where we achieve chemical accuracy.
CCSD(T)+LDA/cc-pVQZ and CCSD(T)+PBE/cc-pVQZ return MAD of 0.33 and 0.31 kcal/mol (respectively) while CCSD(T)/cc-pVQZ still yields a fairly large MAD of 2.50 {\kcal}. CCSD(T)+LDA/cc-pVQZ and CCSD(T)+PBE/cc-pVQZ return MAD of 0.33 and 0.31 kcal/mol (respectively) while CCSD(T)/cc-pVQZ still yields a fairly large MAD of 2.50 {\kcal}.
Therefore, similarly to F12 methods, \cite{TewKloNeiHat-PCCP-07} we can safely claim that the present basis set correction recover quintuple-$\zeta$ quality coupled-cluster correlation energies with triple-$\zeta$ basis sets for a much cheaper computational cost. Therefore, similar to F12 methods, \cite{TewKloNeiHat-PCCP-07} we can safely claim that the present basis set correction recovers quintuple-$\zeta$ quality correlation energies with triple-$\zeta$ basis sets for a much cheaper computational cost.
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\section*{Supporting information} \section*{Supporting information}