76 lines
4.2 KiB
TeX
76 lines
4.2 KiB
TeX
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\documentclass[10pt]{letter}
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\usepackage{UPS_letterhead,xcolor,mhchem,mathpazo,ragged2e}
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\newcommand{\alert}[1]{\textcolor{red}{#1}}
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\definecolor{darkgreen}{HTML}{009900}
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\begin{document}
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\begin{letter}%
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{To the Editors of the Journal of Chemical Physics}
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\opening{Dear Editors,}
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\justifying
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Please find attached a revised version of the manuscript entitled
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\begin{quote}
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\textit{``Chemically accurate excitation energies with small basis sets''},
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\end{quote}
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We would to thank the reviewer for his/her constructive comments.
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Our detailed responses to their comments can be found below.
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For convenience, changes are highlighted in red in the revised version of the manuscript.
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We hope that you will agree that our manuscript is now suitable for publication in JCP.
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We look forward to hearing from you.
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\closing{Sincerely, the authors.}
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%%% REVIEWER 1 %%%
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\noindent \textbf{\large Authors' answer to Reviewer \#1}
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\begin{itemize}
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\item
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{The present paper deals with a recently proposed a-posteriori density-based correction for basis-set incompleteness.
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This correction is derived by projecting the 1/r12 operator onto a finite basis set and on mimicking it point-wise by damped erf(mu*r12)/r12 potentials.
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The effects of the missing short-range potentials are recovered by range-separated correlation-energy density functionals of the LDA or PBE type, modified by asymptotic expressions for large mu.
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In the present paper, the asymptotic expressions are slightly modified, with respect to previous work, and the method is applied to excitation energies of small molecules (CH2 etc.).
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The study is done in a systematic and accurate way, coupling the basis-set corrections to near full-CI calculations for basis sets of increasing quality.
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The results are interesting, and the discussion is clear and physically well motivated.
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On the whole, I feel that the paper is well suited for readers of JCP. }
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\\
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\alert{We thank the reviewer for his/her support.}
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\item
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{The method may be considered as a simple substitute for F12 methods. The latter are
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briefly mentioned, in the Introduction, hinting at difficulties of F12 for excited states.
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It is somewhat unfortunate that no direct comparison to these methods has been attempted
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in the present paper. To my knowledge, there is a recent paper (JCP 150, 184110 (2019)),
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not cited by the present authors, which shows that excitation energies for CH2 (and other
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molecules) can be reliably determined in an F12 context. }
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\\
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\alert{We have cited the recent paper mentioned by the reviewer in the Introduction of our manuscript and added the following sentence:
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\textit{``However, very encouraging results have been reported recently using the extended explicitly-correlated second-order approximate coupled-cluster singles and doubles ansatz suitable for response theory on systems such as methylene, formaldehyde and imidazole.''}
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Unfortunately, the excitation energies provided in the paper mentioned above (obtained at the CC2 level) cannot be directly compared to our results which are obtained at the FCI level.
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We agree with the reviewer that it is unfortunate that no direct comparison to these methods has been yet attempted.
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However, we would like to mention that this is part of our future plan.}
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\item
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{The correction seems to be inappropriate for certain Rydberg excitations (see Fig. 3).
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Is there a possibility to predict such cases? Is the correction meant to recover genuine
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(dynamic) correlation effects only? If yes, then the basis should include enough diffuse
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functions to at least describe the excited Rydberg states at the HF or MCSCF levels. }
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\\
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\alert{Yes, we also agree with the referee that the present correction is inappropriate for certain Rydberg excitations.
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Note that we have explicitly mentioned this several times in our manuscript where we mention that the present correction cannot catch the radial incompleteness of the one-electron basis set, a feature which is far from being a cusp-related effect.
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We have added a sentence to clarify this point: \textit{``In other words, the DFT-based correction recovers dynamic correlation effects only and one must ensure that the basis set includes enough diffuse functions in order to describe Rydberg states.''}}
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\end{itemize}
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\end{letter}
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\end{document}
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