Single-particle spectrum for a model of fermions interacting with two-level local excitations on a lattice: A dynamical CPA approach

TL;DR

This paper analyzes the single-particle spectrum of spinless fermions interacting with two-level systems on a lattice using a dynamical CPA approach, revealing band splitting phenomena.

Contribution

It introduces a dynamical CPA method to study fermion interactions with two-level systems, providing new insights into the density of states and band structure modifications.

Findings

Band splitting occurs with increased coupling strength.

Density of states varies with tunnel splitting and coupling.

Dynamical CPA effectively models electron-two-level system interactions.

Abstract

The problem of motion of a single electron interacting with a periodic lattice of two-level systems is investigated within a spinless fermion model. The Green's function is calculated in a single-site dynamical coherent potential approximation which is equivalent to DMFT. The picture of one-electron density of states is obtained for various values of the tunnel splitting and coupling between the electron and two-level system. The occurrence of a band splitting with increase of the coupling is demonstrated.