Nonadiabatic polarization potentials in electron- and positron-molecule scattering: Application to e(-)+H-2

The nonpenetrating approximation appears to be the simplest way to allow on e to incorporate nonadiabatic effects in the polarization potential calcula ted by means of the polarized orbital method. Unfortunately, this: approxim ation is nor well suited for an efficient implementation in quantum chemist ry codes which, nowadays, use exclusively Gaussian-type orbitals. This comp utational limitation is remedied by replacing the incident point charge by a spherical Gaussian charge distribution, the exponent of which is suitably chosen. In so doing, wt: obtain a very efficient numerical algorithm that may be used with any molecular target regardless of its complexity or geome try. [S1050-2947(99)10201-4].