Sum Rules for Jahn-Teller Reduction Factors

摘要

Jahn-Teller reduction factors (RFs) are a well-known means of comparing the effect of a term in a Hamiltonian on vibronic states with that assuming purely electronic states. First-and second-order RFs occur depending upon the order to which the term occurs in perturbation theory. It is known that there are fundamental sum-rule relations between first-order RFs that arise due to symmetry considerations. First-order sum rule results obtained recently for icosahedral systems are discussed and the ideas are extended to considerations of the corresponding second-order RFs.