SPINLESS PERIODIC ANDERSON MODEL WITH PHONONS AND APPLICATIONS TO MIXED-VALENCE SYSTEMS

A simplified periodic Anderson model, without spin and Hubbard correlation, coupled to a branch of optical phonons is presented and discussed in connection with Rare Earth compounds exhibiting a transition to a mixed valence state. The phonon self energy is approximately calculated by diagrammatic techniques and used for a study of boson modes originating from the interplay of phonons with f-electrons mixed into band states. It is shown that weakly damped low lying or even soft modes may exist in connection with the transition. The relevance of these results to real systems, possible shortcomings of the model and the relations to other work in this field is described. © 1978 Springer-Verlag.