Dynamical two electron states in a Hubbard-Davydov model

TL;DR

This paper investigates the dynamics of two-electron states in a Hubbard-Davydov model, highlighting the role of discrete breathers in localization and their potential significance in high-temperature superconductivity.

Contribution

It introduces a coupled Hubbard-phonon model focusing on two quasi-particles and explores how discrete breathers influence electron localization.

Findings

Discrete breathers significantly affect localization regimes.

Harmonic lattices show weaker localization effects.

Results suggest DBs may be important in high-temperature superconductors.

Abstract

We study a model in which a Hubbard Hamiltonian is coupled to the dispersive phonons in a classical nonlinear lattice. Our calculations are restricted to the case where we have only two quasi-particles of opposite spins, and we investigate the dynamics when the second quasi-particle is added to a state corresponding to a minimal energy single quasi-particle state. Depending on the parameter values, we find a number of interesting regimes. In many of these, discrete breathers (DBs) play a prominent role with a localized lattice mode coupled to the quasiparticles. Simulations with a purely harmonic lattice show much weaker localization effects. Our results support the possibility that DBs are important in HTSC.