Nonequilibrium DMFT+CPA for Correlated Disordered Systems

TL;DR

This paper develops a nonequilibrium method combining DMFT and CPA to study the dynamics of disordered, interacting quantum systems, enabling direct computation of the density of states and relaxation behavior after interaction quenches.

Contribution

It introduces a novel nonequilibrium approach adapting equilibrium DMFT and CPA to real-time dynamics, bypassing analytical continuation for disordered systems.

Findings

Successfully computed the equilibrium density of states without analytical continuation.

Analyzed the relaxation dynamics after an interaction quench in disordered systems.

Demonstrated the impact of disorder on energy relaxation processes.

Abstract

We present a solution for the nonequilibrium dynamics of an interacting disordered system. The approach adapts the combination of the equilibrium dynamical mean field theory (DMFT) and the equilibrium coherent potential approximation (CPA) methods to the nonequilibrium many-body formalism, using the Kadanoff-Baym-Keldysh complex time contour, for the dynamics of interacting disordered systems away from equilibrium. We use our time domain solution to obtain the equilibrium density of states of the disordered interacting system described by the Anderson-Hubbard model, bypassing the necessity for the cumbersome analytical continuation process. We further apply the nonequilibrium solution to the interaction quench problem for an isolated disordered system. Here, the interaction is abruptly changed from zero (non-interacting system) to another constant (finite) value at which it is subsequently kept. We observe via the time-dependence of the potential, kinetic, and total energies, the effect of disorder on the relaxation of the system as a function of final interaction strength. The real-time approach has the potential to shed new light on the fundamental role of disorder in the nonequilibrium dynamics of interacting quantum systems.