Diabatic intermolecular potentials and bound states of open-shell atom–molecule dimers: Application to the F(2P)–H2 complex

Abstract

We present a general derivation of the expansion of diabatic intermolecular potentials for an open-shell atom interacting with a closed-shell molecule and the multipolar expansion of these potentials in the long range. It is outlined how to compute bound states of the open-shell atom–molecule complex from the set of asymptotically degenerate diabatic potentials in a body-fixed basis of rovibrational wave functions with the inclusion of spin–orbit coupling. This method is applied to produce all the bound energy levels of the F(2P)–H2 van der Waals complex with recent diabatic potentials obtained from ab initio calculations by Kłos et al. [Int. J. Quantum Chem. 90, 1038 (2002)]. The binding energy D0 is 14.6 cm−1 for the para-H2 complex and 19.3 cm−1 for the ortho-H2 complex. The para-H2–F complex does not possess any bound states for rotational quantum numbers J larger than 92, the ortho-H2–F complex has a maximum J of 112.