A NEW APPROACH TO INVESTIGATING THE VALENCE FLUCTUATION COMPOUNDS
研究价涨落化合物的一种新方法

The ground state properties of the Sm-based valence fluctuation compounds are discussed by introducing an indirect on-site hybridization mediated by phonons, as the direct on-site hybridization is forbidden by inversion symmetry. The Hamihonian including this indirect hybridization is transformed into an effective Hamihonian of a "small polaron" type by means of a. canonical transformation. A self-consistent field approximation is used, a non-zero energy gap and the noninteger occupation of the f level have been given. The results obtained can be used to explain the small energy gap and the valence fluctuation phenomena observed in SmB6 and SmS.