Four-body singlet potential-energy surface for reactions of calcium monofluoride

A full six-dimensional Born-Oppenheimer singlet potential-energy surface is constructed for the reaction CaF + CaF -> CaF2 + Ca using a multireference configuration-interaction electronic structure calculation. The ab initio data thus calculated are interpolated by Gaussian process regression. The four-body potential-energy surface features one D2h global minimum and one Cs local minimum, connected by a barrierless transition state that lends insight to the reaction mechanism. This surface is intended to be of use in understanding ultracold chemistry of CaF molecules.