A global potential energy surface for H2S+(X 4A) and quasi-classical trajectory study of the S+(4S) + H2(X1Σg+) reaction

A novel global potential energy surface for H2S+(X(4)A) based on accurate ab initio calculations is presented. Energies are calculated at the multi-reference configuration interaction level with Davidson correction using aug-cc-pVQZ basis set plus core-polarisation high-exponent d functions. A grid of 4552 points is used for the least-square fitting procedure in the frame of a many-body expansion. The topographical features of the new potential energy surface are here discussed in detail. Such a surface is then employed for dynamic studies of the S(S-4) + H-2(X-1 Sigma(+)(g)) -> SH+(X-3 Sigma(-)) + H(S-2) reaction using the quasi-classical trajectory method. State specific trajectories are calculated, for both ground and ro-vibrationally excited initial states of H-2(X-1 Sigma(+)(g)). Corrections to the zero point energy leakage of the classical calculations are also presented. Calculated reaction cross sections and rate constants are here reported and compared with available literature.