Semi-empirical potential energy surfaces for alkali atom-dimer exchange reactions

Semi-empirical potential energy surfaces are calculated for the alkali atom-dimer exchange reactions of Li and Na. The surfaces exhibit a potential well at small internuclear distances which extends into the entrance and exit valleys without an energy barrier. The alkali triatomic complex is most stable in the linear or near-linear configuration; it remains stable however over all bent configurations. In the mixed alkali triatomic complex the configuration with the lighter alkali Li in the central position is the more stable; i.e. NaLiLi is more stable than LiNaLi and NaLiNa more stable than NaNaLi. The implications of these surfaces for the reaction dynamics of the alkali atom-dimer exchange reactions are briefly considered.