RELATIVISTIC CONFIGURATION-INTERACTION STUDY OF THE ELECTRONIC-SPECTRUM OF THALLIUM CHLORIDE

An ab initio configuration interaction study including spin-orbit coupling and employing relativistic effective core potentials for both constituent atoms is reported for the lowest lying states of thallium chloride. Good agreement is obtained with measured T(e) values (+/- 1500 cm-1) for all known excited electronic states, as well as with the corresponding equilibrium bond distances and vibrational frequencies. A number of avoided crossings between various OMEGA = 0+ states which are responsible for predissociation effects found by Lindner, Tiemann, and co-workers for this system are described. Details of the asymptotic behavior of the various potential curves leading to the Tl(2P(u)) + Cl(2P(u)) atomic limits are faithfully reproduced in the calculations, and estimates of the radiative lifetimes of key vibrational states are also given. (C) 1994 Academic Press, Inc.