Potential Energy Surface for Ground-State H2S via Scaling of the External Correlation, Comparison with Extrapolation to Complete Basis Set Limit, and Use in Reaction Dynamics

A global double many-body expansion potential energy surface is reported for the electronic ground state of H2S by fitting accurate ab initio energies calculated at the multireference configuration interaction level with the aug-cc-pVQZ basis set, after slightly correcting semiempirically the dynamical correlation by the double many-body expansion-scaled external correlation method. The function so obtained has been compared in detail with a potential energy surface of the same type recently reported (Song, Y. Z.; Varandas, A. J. C. J. Chem. Phys. 2009, 130, 134317.) by extrapolating the calculated raw energies to the complete basis set limit, eschewing any use of information alien to ab initio theory. The new potential energy surface is also used for studying the dynamics and kinetics of the S(D-1) + H-2/D-2/HD reactions.