Collisional polarizabilities of the inert gases

We extend our previous work on collisional pair polarizabilities by including overlap effects through second order and by explicitly computing the contributions from exchange and correlation in the region of small orbital overlap. We apply the theory to the calculation of pair polarizabilities (both the anisotropy and the trace) of inert gas diatoms. The agreement with coupled Hartree-Fock calculations and experimental optical properties is good, and suggests that this simple method should provide a feasible approach for similar descriptions of molecular gases.