Ham factors in multi-mode Jahn-Teller systems

Abstract

Calculations have been made of the multi-mode corrections required for some of the reduction factors for an E electronic state coupled simultaneously to phonon modes of different frequencies. Numerical calculations for two modes, with a variety of coupling strength and frequency ratios, are used to interpolate between analytic calculations valid for many modes at strong and weak coupling. The corrections to the reduction factors calculated using the appropriate cluster model are found to be relatively small, and cannot reasonably fit some of the corrections deduced from experiment. Linear Jahn-Teller coupling and harmonic phonons are assumed through most of the work, but some preliminary calculations have been made of the corrections to be expected at strong coupling, when anharmonicity is important.