Nonequilibrium dynamical mean-field theory of a strongly correlated system

TL;DR

This paper develops a nonequilibrium dynamical mean-field theory using Keldysh formalism to analyze strongly correlated systems under time-dependent external fields, deriving self-consistency equations and calculating optical conductivity.

Contribution

It introduces a generalized nonequilibrium DMFT framework with self-consistency equations for driven systems, applying it to the Hubbard model with numerical results.

Findings

Numerical Green's functions and self-energies for various field amplitudes.

Derived expression for optical conductivity under external driving.

Validated the approach with iterative perturbation theory.

Abstract

We present a generalized dynamical mean-field approach for the nonequilibrium physics of a strongly correlated system in the presence of a time-dependent external field. The Keldysh Green's function formalism is used to study the nonequilibrium problem. We derive a closed set of self-consistency equations in the case of a driving field with frequency Omega and wave vector q. We present numerical results for the local frequency-dependent Green's function and the self-energy for different values of the field amplitude in the case of a uniform external field using the iterated perturbation theory. In addition, an expression for the frequency-dependent optical conductivity of the Hubbard model with a driving external field is derived.