Analytic potential surfaces and diabatic interaction matrix elements between electronic states in the inert gas atom-halogen molecule system: Ion-pair states

The electronic structure of complexes between halogen molecules in the ion-pair state and inert gas atoms was studied in the diatomic s-in-molecule approximation using first-order perturbation theory with respect to intermolecular interaction. Analytic representations for fragment matrices and formulas that determine potential energy surfaces and diabatic interactions in complexes in first-tier ion-pair states were obtained. The developed approach was used to describe the electronic structure of the Ar-I-2 system. The interaction potentials of the Ar-I+ and Ar-I- diatomic fragments used to parametrize the model were obtained in ab initio calculations. The topology and energy of potential surfaces and the symmetry properties of interaction matrix elements were characterized.