Influence of Spatial Correlations in Strongly Correlated Electron Systems: Extension to Dynamical Mean Field Approximation

TL;DR

This paper introduces a formalism to incorporate spatial fluctuation corrections into the dynamical mean-field approximation, revealing effects like pseudogap behavior and enhanced specific heat in strongly correlated electron systems.

Contribution

It extends the dynamical mean-field approximation by including spatial correlations through a new formalism and approximate susceptibility, providing insights into spectral and thermodynamic properties.

Findings

Observation of pseudogap behavior in the spectral intensity.

Enhanced specific heat due to short-range order.

Reduction of double occupancy indicating Mott localization.

Abstract

We propose a formalism to take account of the correction of the spatial fluctuations to the local self-energy obtained by the dynamical mean-field approximation. For this purpose, the approximate dynamical susceptibility in the framework of the iterated perturbation theory is proposed and examined. Using the formalism, it is demonstrated that the one-particle spectral intensity in the two-dimensional Hubbard model at half-filling exhibits the pseudo-gap behavior in the central coherent quasiparticle peak due to the critical antiferromagnetic fluctuation. The specific heat is considerably enhanced by the short-range order, which assists a tendency of the Mott localization showing the reduction of the double occupancy. We briefly discuss a formulation for the superconducting transition temperature in the present approximation.