A globally accurate potential energy surface of $$\mathrm{HS_2}{(A\,^2A^\prime )}$$ HS 2 ( A 2 A ′ ) and studies on the reaction dynamic of $$\mathrm{H}(^2\mathrm{S})+\mathrm{S_2}(a\,^1{\varDelta }_g)$$ H ( 2 S ) + S 2 ( a 1 Δ g )

Abstract

A global potential energy surface (PES) for the first excited electronic state of $$\mathrm{HS_2}$$ is reported. Analytic representation of the PES is accomplished in the frame of a many-body expansion. A grid of 2069 ab initio points is used in the least-square fitting procedure. Calculations are carried out at the multireference configuration interaction level, using the complete active space wave function as reference. The aug-cc-pVQZ Dunning’s basis set is used. Topographical features of main stationary points of the PES are presented and compared with the literature. The newly obtained function is then used in quasi-classical trajectory calculations for $$\mathrm{H}(^2\mathrm{S})+\mathrm{S_2}(a\,^1{\varDelta }_g)$$ $$\rightarrow$$ $$\mathrm{SH}(X\,^2{\varPi }) + \mathrm{S} (^3P)$$ reaction. Differential and integral cross section for such a reaction is here calculated. State-specific reaction rate constant is presented as well.