Accurate global potential energy surface for the ground state of CH2+ by extrapolation to the complete basis set limit

Abstract

A full three-dimensional global potential energy surface is reported for the ground state of CH₂⁺ by fitting accurate multireference configuration interaction energies calculated using aug-cc-pVQZ and aug-cc-pV5Z basis sets with extrapolation of the electron correlation energy to the complete basis set limit. The topographical characteristics have been compared in detail with a potential energy surface of the same type recently reported [J. Chem. Phys., 2015, 142, 124302] based on a least-squares fit to accurate high level ab initio MRCI(Q) energies, calculated using AV6Z basis set. The new three-dimensional global potential energy surface is then used in quasiclassical trajectory calculations for H(²S) + CH⁺(X¹Σ⁺) → C⁺(²P) + H₂(X¹Σ_g⁺) reaction. The integral cross sections, differential cross sections and the rate coefficients have been computed. A comparison shows that our potential energy surface can be applied to any type of dynamic study.