Ab initio conical intersections for the Si(1D) + H2 reaction system: a lowest five singlet states study

Abstract

Conical intersection (CI) play a key role in the non-adiabatic processes and the geometric phase (GP) effect associated with CI have a significant influence on the quantum reactive scattering and bound-state calculations. In this work, the CIs and the GP effects associated with the CIs of the Si(¹D) + H₂ system are investigated using the internally contracted multireference configuration intersection method for the first time. The seams of the CIs (at the linear H–Si–H geometries, linear Si–H–H geometries and C_2v geometries) among the lowest five singlet states relative to the Si(¹D) + H₂ reaction system are searched systematically. The properties of minimum energy crossing points (MECPs) of these intersection seams are determined, the topographies of the potential energy surfaces in the branching spaces of MECPs and the GP effects associated with the CIs are discussed.