Ab Initio Calculation of CN Free Radical Using MRD-CI

Ab initio MRD-CI calculations were carried out for the low lying states of CN. The potential curves for the X~2∑~+ ground state and A~2∏~+ excited state were determined. The bond lengths of the two states were found to be in good agreement with the experimental results. The spectroscopic constants of the two states were obtained by solving the Schodinger equation with the obtained potential energy. And the rotational constants' first three digits are found significant after comparing with the experimental values.