Accurate Explicit-Correlation-MRCI-Based DMBE Potential-Energy Surface for Ground-State CNO

We report a new global double many-body expansion potential energy surface for the ground state of the CNO(²A') manifold, calculated by the explicit correlation multireference configuration interaction method. The functional form was accurately fitted to 3701 ab initio points with a root mean squared deviation of 0.99 kcal mol^-1. All stationary points reported in previous forms are systematically described and improved, in addition to three new ones and a characterization of an isomerization transition state between the CNO and NCO minima. The novel proposed form gives a realistic description of both short-range and long-range interactions and hence is commended for dynamics studies.