Density functional formulation of collisional polarizabilities: Application to homonuclear noble gas diatoms

We apply the general density functional formalism for electron gases in external fields to the specific case of electric susceptibilities of interacting closed shell systems. Computations are presented for the parallel and perpendicular components of the incremental polarizability tensors of He2, Ne2, and Ar2, as functions of internuclear distance. In the case of He2 our results can be compared with recent coupled Hartree−Fock calculations. For all three of the light noble gases we have evaluated the thermal averages of the pair polarizability components which correspond to the second dielectric virial coefficients and low pressure light depolarization ratios: Agreement with experimental data is found to be very good. The dependence of these calculated collision−induced optical properties on interatomic potentials and the long range behavior of the pair polarizability are considered in detail.