AN ADIABATIC MODEL FOR RARE-GAS HALOGEN VAN-DER-WAALS COMPLEXES - APPLICATION TO HEBR2(B)

An adiabatic approach to compute quasibound states of rare gas-halogen van der Waals molecules is presented where the interhalogen vibration al coordinate is considered as the 'slow' mode (i.e. it takes the plac e of the nuclear coordinates in the traditional Born-Oppenheimer separ ation). Although it might not seem intuitive (as far as the halogen vi brational motion is not slower than the intermolecular one), it is sho wn that a satisfactory (zero order) picture is provided for those stat es where the halogen subunit is near dissociation. The method is appli ed to HeBr2 (B,v), for which experimental data at very high v are avai lable. Results are discussed in light of comparisons with 'exact' clos e-coupling calculations. (C) 1998 Published by Elsevier Science B.V. A ll rights reserved.