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

A full three-dimensional global potential energy surface is reported for the ground state of CH 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 [, 2015, , 124302] based on a least-squares fit to accurate high level 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(S) + CH( Σ) → C(P) + H( Σ ) 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.