Initial correlations in nonequilibrium Falicov-Kimball model

TL;DR

This study investigates the role of initial correlations in the nonequilibrium Falicov-Kimball model using dynamical mean-field theory, revealing their importance in accurately capturing electron dynamics, especially under strong interactions.

Contribution

It provides a detailed analysis of initial correlations' effects on nonequilibrium properties, highlighting their significance in strong interaction regimes within the Falicov-Kimball model.

Findings

Initial correlations are crucial for full electron correlation development.

Neglecting initial correlations can lead to artifacts in nonequilibrium properties.

The impact of initial correlations increases with interaction strength.

Abstract

The Keldysh boundary problem in a nonequilibrium Falicov-Kimball model in infinite dimensions is studied within the truncated and self-consistent perturbation theories, and the dynamical mean-field theory. Within the model the system is started in equilibrium, and later a uniform electric field is turned on. The Kadanoff-Baym-Wagner equations for the nonequilibrium Green functions are derived, and numerically solved. The contributions of initial correlations are studied by monitoring the system evolution. It is found that the initial correlations are essential for establishing full electron correlations of the system and independent on the starting time of preparing the system in equilibrium. By examining the contributions of the initial correlations to the electric current and the double occupation, we find that the contributions are small in relation to the total value of those physical quantities when the interaction is weak, and significantly increase when the interaction is strong. The neglect of initial correlations may cause artifacts in the nonequilibrium properties of the system, especially in the strong interaction case.