Abstract
We constructed a new global potential energy surface (PES) for the electronic ground state (1A′) of H2S based on 21,300 accurate ab initio energy points over a large configuration space. The ab initio energies are obtained from multireference configuration interaction calculations with a Davidson correction using basis sets of quadruple zeta quality. The neural network method is applied to fit the PES, and the root mean square error of fitting is small (1.68 meV). Time-dependent wave packet studies for the S(1D) + H2(X1Σg+) → H(2S) + SH(X2Π) reaction on the new PES are conducted to study the reaction dynamics. The calculated integral cross sections decrease with increasing collision energy and remain fairly constant within the high collision energy range. Both forward and backward scatterings can be observed as expected for a barrierless reaction with a deep well on the PES. The calculated integral cross sections and differential cross sections are in good agreement with the experimental results.
Highlights
IntroductionThe S(1D) + H2(X1Σ g+) → H(2S) + SH(X2Π ) reactive system and its isotopic variants have been studied both experimentally[1,2,3,4,5,6,7] and theoretically[8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26]
Reaction dynamics in the low temperature regime have attracted a great deal of attention, because the information on reactive processes within the very low kinetic energy range can be explored by newly developed experimental techniques
We report a new global potential energy surface (PES) for the electronic ground state of the H2S system
Summary
The S(1D) + H2(X1Σ g+) → H(2S) + SH(X2Π ) reactive system and its isotopic variants have been studied both experimentally[1,2,3,4,5,6,7] and theoretically[8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26]. In 2012, the ICSs for the two channels of the S(1D) + H D reaction were obtained through crossed-beam experiments down to 0.46 meV.[7] On the reactive path of the S(1D) + H2(X1Σ g+) → H(2S) + SH(X2Π ) reaction, there is a deep and wide well in which the long-life complex can form at a low collision energy; it can be expected that the dynamics results are extremely sensitive to the PES. Our major goal is to construct an accurate global PES for the H2S (1A′ ) system, which can meet the requirements above To achieve this objective, we calculated a mass of ab initio energy points in a large region of configuration space, and used the neural network (NN) method to fit the new PES. Time-dependent wave packet (TDWP) calculations were conducted for the S(1D) + H2(X1Σ g+) → H(2S) + SH(X2Π ) reaction to study the reactive mechanism and verify the new PES
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