High-level ab initio potential energy surfaces and vibrational energies of H2CS

摘要

Six-dimensional (6D) potential energy surfaces (PESs) of H2CS have been generated ab initio us-ning the recently proposed explicitly correlated (F12) singles and doubles coupled cluster methodnincluding a perturbational estimate of connected triple excitations, CCSD(T)-F12b [T. B. Adler,nG. Knizia, and H.-J.Werner, J. Chem. Phys. 127, 221106 (2007)] in conjunction with F12-optimizedncorrelation consistent basis sets. Core-electron correlation, high-order correlation, scalar relativistic,nand diagonal Born-Oppenheimer terms were included as additive high-level (HL) corrections. Thenresulting 6D PESs were represented by analytical functions which were used in variational calcula-ntions of the vibrational term values below 5000 cm−1n. The best PESs obtained with and without thenHL corrections, VQZ-F12∗HL and VQZ-F12∗n, reproduce the fundamental vibrational wavenumbersnwith mean absolute deviations of 1.13 and 1.22 cm−1n, respectively. A detailed analysis of the effectsnof the HL corrections shows how the VQZ-F12 results benefit from error cancellation. The presentnpurely ab initio PESs will be useful as starting points for empirical refinements towards an accurate