A global potential energy surface for H 2 S + (X 4A′′) and quasi-classical trajectory study of the S + (4S) + H 2 (X1Σ+ g) reaction

Abstract

ABSTRACT 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(4 S) + H2(X 1Σ+ g ) →SH+(X 3Σ−) + H(2 S) reaction using the quasi-classical trajectory method. State specific trajectories are calculated, for both ground and ro-vibrationally excited initial states of H2(X 1Σ+ 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.