Electronic spectral properties of the two-dimensional infinite-U Hubbard model

TL;DR

This study compares two advanced theoretical methods to analyze the electronic spectral properties of the two-dimensional infinite-U Hubbard model, revealing insights into quasiparticle behavior and spectral skewness in strongly correlated regimes.

Contribution

It introduces a combined use of strong-coupling series expansion and ECFL theory to accurately compute spectral moments and analyze spectral features in the infinite-U Hubbard model.

Findings

Good agreement between methods at various densities and temperatures.

Modified first moment effectively describes quasiparticle peak location.

Spectral function is skewed towards occupied states at low temperatures.

Abstract

A strong-coupling series expansion for the Green's function and the extremely-correlated Fermi liquid (ECFL) theory are used to calculate the moments of the electronic spectral functions of the infinite-U Hubbard model. Results from these two complementary methods agree very well at both, low densities, where the ECFL solution is the most accurate, and at high to intermediate temperatures, where the series converge. We find that a modified first moment, which underestimates the contributions from the occupied states and is accessible in the series through the time-dependent Green's function, best describes the quasiparticle peak location in the strongly-correlated regime. This is examined by the ECFL results at low temperatures, where it is shown that the spectral function is largely skewed towards the occupied states.