New theory of the fine structure of donor-acceptor pairs

Following a summary of existing theories, a new theory is proposed which predicts both the magnitude and the $r$ dependence for type-I "inverse-set" donor-acceptor pair splittings. The physical origin of the multipole potentials is the anisotropic contribution to dielectric polarization made by the induced dipoles on the four nearest neighbors of a donor or acceptor. The systematics of both the magnitude and $r$ dependence of the spectra are accounted for by the integration of these multipole potentials over the donor and acceptor electronic charge densities.