Models for bond distance dependent alkali dimerndash;rare gas potentials

摘要

Analytic expressions for Li2ndash;Rg and Na2ndash;Rg electronic ground state potentials (Rg=He,Ne,Ar,Kr,Xe) that depend on all three Jacobian coordinates, atomndash;molecule distanceR, bond lengthr, and orientation angle ggr;, are presented. The potentials are obtained by expanding the repulsive and attractive parts in a twohyphen;term Legendre expansion and connecting them via generalized damping functions as proposed by Tang and Toennies lsqb;J. Chem. Phys.80, 3726 (1984)rsqb;. The bond distance dependence (req=5.051 a.u.le;rle;6.838 a.u. for Li2andreq=5.809 a.u.le;rle;7.607 a.u. for Na2) is introduced in the repulsive part via therhyphen;dependent shift of the repulsive barrier and in the attractive part via therdependence of the multipole polarizabilities and effective excitation energies. These potentials are shown to agree reasonably withabinitiodata. The resulting values of potential well depth egr; and equilibrium distanceRmare used to check the validity of recently proposed direct combining rules forrhyphen;dependent potentials.