Simple semiempirical potential energy surfaces for the reaction of alkali metal atoms with the bromine molecule

Potential energy surfaces for the reactions of the alkali metals M (Li, Na, K, Rb, and Cs) with Br2 are computed using a simple semiempirical procedure. The calculations show that there is a vibrational barrier between M+Br2 and M++Br2− along the Br–Br coordinate which plays an important role in the reaction. A potential well exists for all angles of approach of the metal to the molecule; this M+Br2− species is lower in energy than any product channel. The calculated ionic/covalent coupling matrix elements between M+Br2 and M++Br2− agree well with the experimental values.