Spin-orbit coupling in I center dot CO2 and I center dot OCS van der Waalscomplexes: beyond the pseudo-diatomic approximation

We investigate theoretically the electronic structure of I . CO2 and I . OC S van der Waals complexes including spin-orbit interaction. For the T-shape d geometry of I . CO2, we calculate the potentials using a fully polyatomic treatment and compare the results to the widely used pseudo-diatomic appro ximation. The latter becomes: increasingly invalid at I-CO2 distances shelt er than 4 Angstrom. We calculate the potentials of linear I . SCO and I . O CS, and analyze the zero-order electronic structure of nonlinear I . OCS. W e also discuss the validity of treating the spin-orbit interaction in I . C O2 and I . OCS as an atomic property of iodine and find this approximation justified at characteristic van der Weals distances. (C) 1999 Elsevier Scie nce B.V. All rights reserved.