Thermodynamic properties and thermal correlation lengths of a Hubbard model with bond-charge interaction

TL;DR

This paper studies the thermodynamic behavior of a one-dimensional Hubbard model with bond-charge interaction using TMRG, revealing phase characteristics and correlation behaviors at finite temperatures.

Contribution

It provides detailed numerical analysis of thermodynamic quantities and correlation lengths, comparing with exact and bosonization results, confirming phase existence and correlation dominance.

Findings

Confirmation of Tomonaga-Luttinger and Luther-Emery phases

Thermal singlet-pair correlations dominate in certain regimes

Excellent agreement with exact and bosonization results

Abstract

We investigate the thermodynamics of a one-dimensional Hubbard model with bond-charge interaction X using the transfer matrix renormalization group method (TMRG). Numerical results for various quantities like spin and charge susceptibilities, particle densities, specific heat and thermal correlation lengths are presented and discussed. We compare our data also to results for the exactly solvable case X/t=1 as well as to bosonisation results for weak coupling X/t << 1, which shows excellent agreement. We confirm the existence of a Tomonaga-Luttinger and a Luther-Emery liquid phase, in agreement with previous studies at zero temperature. Thermal singlet-pair correlation lengths are shown to dominate density and spin correlations for finite temperatures in certain parameter regimes.