These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
SVECV-f12_Sent_12312019_Main_Text.pdf (909.53 kB)
SVECV-F12: A Composite Scheme for an Accurate and Cost Effective Evaluation of Reaction Barriers. I. Benchmarking Using the HTBH38/08 and NHTBH38/08 Barrier Heights Databases
Preprints are manuscripts made publicly available before they have been submitted for formal peer review and publication. They might contain new research findings or data. Preprints can be a draft or final version of an author's research but must not have been accepted for publication at the time of submission.
A simple version of a composite scheme is described, based on a combination of density functional geometry and frequencies evaluation, valence energies obtained using the CCSD(T)-f12 method extrapolated to the complete basis set limit, and core-valence correlation corrections employing the MP2 method. The procedure was applied to the 38 reactions in Truhlar’s HTBH38/08 and NHTBH38/08 databases. Mean unsigned deviation (MUD) for the complete set of 68 independent barriers is 0.43 kcal mol-1, compared to 1.37 kcal/mol for G4 and 1.69 kcal/mol for the dispersioncorrected M06-2X method. Its accuracy is also better that that of other calculations using composite methods of similar cost. The MUD of the new scheme on the barriers in the DBH24/08 subset (12 out of the 38 reactions in both other sets) is 0.31 kcal mol-1, better than that obtained at the expensive CCSD(T,full)/aug-cc-pCV(T+d)Z level (0.46 kcal mol-1) and comparable to the most exact (and costly) Wn calculations (MUD=0.14 kcal mol-1). The maximum unsigned deviation (MaxUD) of the new method for all the reactions studied is 1.71 kcal/mol. G4 and M06-2X, on the other side, exhibit MaxUDs of 6.7 and 8.4 kcal/mol respectively