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On the accuracy of explicitly correlated coupled-cluster interaction energies - have orbital results been beaten yet?


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dc.contributorKonrad Patkowski, kjp0013@auburn.eduen_US
dc.creatorPatkowski, Konrad
dc.date.accessioned2020-08-20T15:35:06Z
dc.date.available2020-08-20T15:35:06Z
dc.date.created2012
dc.identifier10.1063/1.4734597en_US
dc.identifier.urihttps://aip.scitation.org/doi/pdf/10.1063/1.4734597en_US
dc.identifier.urihttps://aurora.auburn.edu/handle/11200/49923
dc.identifier.urihttp://dx.doi.org/10.35099/aurora-11
dc.description.abstractThe basis set convergence of weak interaction energies for dimers of noble gases helium through krypton is studied for six variants of the explicitly correlated, frozen geminal coupled-cluster singles, doubles, and noniterative triples [CCSD(T)-F12] approach: the CCSD(T)-F12a, CCSD(T)- F12b, and CCSD(T)(F12*) methods with scaled and unscaled triples. These dimers were chosen because CCSD(T) complete-basis-set (CBS) limit benchmarks are available for them to a particularly high precision. The dependence of interaction energies on the auxiliary basis sets has been investigated and it was found that the default resolution-of-identity sets cc-pVXZ/JKFIT are far from adequate in this case. Overall, employing the explicitly correlated approach clearly speeds up the basis set convergence of CCSD(T) interaction energies, however, quite surprisingly, the improvement is not as large as the one achieved by a simple addition of bond functions to the orbital basis set. Bond functions substantially improve the CCSD(T)-F12 interaction energies as well. For small and moderate bases with bond functions, the accuracy delivered by the CCSD(T)-F12 approach cannot be matched by conventional CCSD(T). However, the latter method in the largest available bases still delivers the CBS limit to a better precision than CCSD(T)-F12 in the largest bases available for that approach. Our calculations suggest that the primary reason for the limited accuracy of the large-basis CCSD(T)-F12 treatment are the approximations made at the CCSD-F12 level and the non-explicitly correlated treatment of triples. In contrast, the explicitly correlated second-order Møller-Plesset perturbation theory (MP2-F12) approach is able to pinpoint the complete-basis-set limit MP2 interaction energies of rare gas dimers to a better precision than conventional MP2. Finally, we report and analyze an unexpected failure of the CCSD(T)-F12 method to deliver the core-core and core-valence correlation corrections to interaction energies consistently and accurately. ©en_US
dc.formatPDFen_US
dc.publisherAIP Publishingen_US
dc.relation.ispartofJournal of Chemical Physicsen_US
dc.relation.ispartofseries0021-9606en_US
dc.subjectCCSD(T) interaction energies noble gas helium krypton couple-cluster single noninterative tripleen_US
dc.titleOn the accuracy of explicitly correlated coupled-cluster interaction energies - have orbital results been beaten yet?en_US
dc.typeTexten_US
dc.type.genreJournal Article, Academic Journalen_US
dc.citation.volume137en_US
dc.citation.issue3en_US
dc.citation.spage34103-1en_US
dc.citation.epage34103-18en_US
dc.description.statusPublisheden_US
dc.description.peerreviewyesen_US

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