With the many-body expansion method, an accurate global potential energy surface (PES) is constructed for SiH2+(X2A1) by mapping 4762 ab initio energy points calculated on the multireference configuration interaction level including Davidson corrections with aug-cc-pV6Z Dunning’s basis set. The dissociation energies and equilibrium geometries of SiH+(X1Σ+) and H2(X1Σg+) agree well with the experimental results. The topographical characteristics of all stationary points for the SiH2+(X2A1) PES are discussed in detail and compared with other theoretical and experimental results. In order to verify the validity and usability of the present PES, the dynamics calculations based on the Chebyshev quantum wave packet method are performed for the H(S2)+SiH+(X1Σ+)→Si+(P2)+H2(X1Σg+) reaction. The probabilities, the total integral cross sections, and the rate constants are computed, and the analogies with the corresponding ones of reaction H(S2) + CH+(X1Σ+)→C+(P2) + H2(X1Σg+) are also made. The reasonable dynamical behavior throughout the entire configuration space indicates that the PES is suitable for relevant dynamics investigations and serves as a building block for constructing the PES of larger molecular systems containing Si+/H.

The single-sheeted potential energy surface (PES) of H2S+(X 2A′′) is developed based on the ab initio energies calculated by the multi-reference configuration interaction method including the Davidson correction. All the ab initio energies are first calculated using aug-cc-pVQdZ and aug-cc-pV5dZ basis sets, which are then extrapolated to the complete basis set (CBS) limit. A switching function is developed to model the transition of S+D2 to S+S4. The many-body expansion formalism is employed to obtain the H2S+(X 2A′′) PES by fitting such CBS energies and the root-mean square derivation is 0.0367 eV. The topographical features of the present PES are examined in detail, which are well consistent with previous studies. The quasiclassical trajectory method is subsequently utilized to study the S+D2+H2(X1Σg+) → SH+(X 3Σ−)+H(S2) reaction. The capture time, integral cross sections, and rovibrational distributions are calculated. By examining the capture time, it can be concluded that the title reaction is mainly controlled by the indirect mechanism for lower collision energies, while the direct and indirect mechanisms coexist and the latter plays a dominant role for higher collision energies.

A globally accurate many-body expansion potential energy surface is reported for HCS(X2A′) by fitting a wealth of accurate ab initio energies calculated at the multireference configuration interaction level using aug-cc-pVQZ and aug-cc-pV5Z basis sets via extrapolation to the complete basis set limit. The topographical features of the present potential energy surface are examined in detail and is in good agreement with the raw ab initio results, as well as other theoretical results available in literatures. By utilizing the potential energy surface of HCS(X2A′), the dynamic studies of the C(3P) + SH(X2Π) → H(2S) + CS(X1∑+) reaction has been carried out using quasi-classical trajectory method.

The dependence of the cross section for the C + SH  H + CS, S + CH reactions on the vibrational excitation of SH(v = 0-20, j = 0) is analyzed in detail at the collision energies of 0.3 and 0.8 eV by using the quasi-classical trajectory method and the new potential energy surface). The efficiency of vibrational excitation to promote the reaction is investigated through the analysis of the cross section and its v dependence in terms of the reaction probability, maximum impact parameter, and the features of the potential energy surface. The differential cross sections obtained show that at higher vibrational levels, the products (CS, CH) are mainly forward scattered, and the sideward and backward scatterings are quite weak. In addition to the scalar properties, the stereodynamical attributes, such as angle distribution functions P(θ r ), P(f r ) and P(θ r , f r ) at different vibrational levels are explored in detail. Furthermore, through the investigation of the state-to-state dynamics for the titled reaction, it is clear that the vibrational excitation of the product for C + SH  H + CS reaction is quite strong, with the most probable population appearing at high vibration numbers.