AB-INITIO CALCULATIONS OF THE GROUND AND EXCITED-STATES OF I-2(-) ANDICL-

We performed all-electron ab initio calculations of the first six stat es of I-2(-) and ICl- using a multi-reference configuration interactio n method. Spin-orbit coupling is included via an empirical one-electro n operator and has a large effect on the dissociation energy. The grou nd state dissociation energies were in error by 20-30%, probably due t o deficiencies in the one electron basis sets. The electronic wavefunc tions at the equilibrium geometry were used to calculate the electroni c absorption spectrum from the ground state, and good agreement was fo und with the experimental data.