Accurate global potential energy surface for the ground state of CH 2 + by extrapolation to the complete basis set limit.

A full three-dimensional global potential energy surface is reported for the ground state of CH 2 + 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( 2 S) + CH + ( X 1 Σ + ) → C + ( 2 P) + H 2 ( X 1 Σ 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.