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We extrapolate to the perturbative triples (T)/complete basis set (CBS) limit using double zeta basis sets without polarization functions (Wesleyan-1-Triples-2zeta or "Wes1T-2Z") and triple zeta basis sets with a single level of polarization functions (Wesleyan-1-Triples-3zeta or "Wes1T-3Z"). These basis sets were optimized for 102 species representing the first two rows of the Periodic Table. The species include the entire set of neutral atoms, positive and negative atomic ions, as well as several homonuclear diatomic molecules, hydrides, rare gas dimers, polar molecules, such as oxides and fluorides, and a few transition states. The extrapolated Wes1T-(2,3)Z triples energies agree with (T)/CBS benchmarks to within +/-0.65 mEh, while the rms deviations of comparable model chemistries W1, CBS-APNO, and CBS-QB3 for the same test set are +/-0.23 mEh, +/-2.37 mEh, and +/-5.80 mEh, respectively. The Wes1T-(2,3)Z triples calculation time for the largest hydrocarbon in the G2/97 test set, C6H5Me(+), is reduced by a factor of 25 when compared to W1. The cost-effectiveness of the Wes1T-(2,3)Z extrapolation validates the usefulness of the Wes1T-2Z and Wes1T-3Z basis sets which are now available for a more efficient extrapolation of the (T) component of any composite model chemistry.

1 citations (Crossref) [2023-10-31] Place: United States Ranasinghe, Duminda S. Hall-Atwater Laboratories of Chemistry, Wesleyan University, Middletown, Connecticut 06459-0180, USA. Barnes, Ericka C. Department of Chemistry, Southern Connecticut State University, 501 Crescent Street, New Haven, Connecticut 06515-1355, USA.