Eur. Phys. J. B (2015) 88: 108
https://doi.org/10.1140/epjb/e2015-50528-5

Regular Article

Effect of electron-phonon interaction and external magnetic field on the bound state in the Anderson-Holstein model: an improved variational treatment

School of Physics, University of Hyderabad, 500046 Hyderabad, India

^a e-mail: acsp@uohyd.ernet.in

Received: 5 August 2014
Received in final form: 12 December 2014
Published online: 4 May 2015

Abstract

The single-impurity Anderson-Holstein model is investigated in the presence of a magnetic field by an improved variational method. The phonon degrees of freedom are first eliminated by a modified Lang-Firsov transformation followed by a zero-phonon averaging. The resulting Hamiltonian is then treated by a cluster variational method to study the effects of the electron-phonon interaction and the magnetic field on the ground state energy, local magnetic moment and the binding energy between the magnetic impurity and the conduction electrons.