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 $+$ $\ensuremath{\rightarrow}\phantom{\rule{4pt}{0ex}}{\mathrm{CaF}}_{2} +$ Ca using a multireference configuration-interaction electronic structure calculation. The ab initio data thus calculated are interpolated by Gaussian process regression. four-body features one ${D}_{2h}$ global minimum and ${C}_{s}$ local minimum, connected barrierless transition state that lends insight to mechanism. This intended be of use in understanding ultracold chemistry molecules.