Accurate global potential energy surface for SiH2+(X2A1) and quantum dynamics of related reaction H(2S) + SiH+(X1Σ+)

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.