First-Principles Theory of the Momentum-Dependent Local Ansatz for Correlated Electron System

TL;DR

This paper develops a first-principles version of the momentum-dependent local-ansatz wavefunction to better describe correlated electrons in solids, demonstrating improved accuracy in modeling electron correlations and momentum distribution.

Contribution

The authors extend the MLA to a first-principles framework using LDA+U Hamiltonian, enabling realistic modeling of correlated electron systems.

Findings

Successfully applied to paramagnetic Fe, showing reasonable correlation energy gain.

Demonstrated suppression of charge fluctuations due to electron correlations.

Revealed a distinct momentum dependence of the momentum distribution.

Abstract

The momentum-dependent local-ansatz (MLA) wavefunction describes well correlated electrons in solids in both the weak and strong interaction regimes. In order to apply the theory to the realistic system, we have extended the MLA to the first-principles version using the tight-binding LDA+U Hamiltonian. We demonstrate for the paramagnetic Fe that the first-principles MLA can describe a reasonable correlation energy gain and suppression of charge fluctuations due to electron correlations. Furthermore, we show that the MLA yields a distinct momentum dependence of the momentum distribution, and thus improves the Gutzwiller wavefunction.