Extrapolation of high-order correlation energies: The WMS model

Yan Zhao, Lixue Xia, Xiaobin Liao, Qiu He, Maria X. Zhao, Donald G. Truhlar

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

We have developed a new composite model chemistry method called WMS (Wuhan-Minnesota scaling method) with three characteristics: (1) a composite scheme to approximate the complete configuration interaction valence energy with the affordability condition of requiring no calculation more expensive than CCSD(T)/jul-cc-pV(T+d)Z, (2) low-cost methods for the inner-shell correlation contribution and scalar relativistic correction, and (3) accuracy comparable to methods with post-CCSD(T) components. The new method is shown to be accurate for the W4-17 database of 200 atomization energies with an average mean unsigned error (averaged with equal weight over strongly correlated and weakly correlated subsets of the data) of 0.45 kcal mol-1, and the performance/cost ratio of these results compares very favorably to previously available methods. We also assess the WMS method against the DBH24-W4 database of diverse barrier heights and the energetics of the reactions of three strongly correlated Criegee intermediates with water. These results demonstrate that higher-order correlation contributions necessary to obtain high accuracy for molecular thermochemistry may be successfully extrapolated from the lower-order components of CCSD(T) calculations, and chemical accuracy can now be obtained for larger and more complex molecules and reactions.

Original languageEnglish (US)
Pages (from-to)27375-27384
Number of pages10
JournalPhysical Chemistry Chemical Physics
Volume20
Issue number43
DOIs
StatePublished - Jan 1 2018

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