Dynamical density-density correlations in one-dimensional Mott insulators

TL;DR

This paper investigates the dynamical density-density correlations in one-dimensional Mott insulators, combining numerical and analytical methods to reveal excitonic features across different parameters.

Contribution

It provides a combined numerical and analytical analysis of density correlations in the extended Hubbard model, highlighting excitonic effects at the zone boundary.

Findings

Excitonic features exist at the zone boundary for any finite nearest neighbor repulsion.

Most spectral weight at the zone boundary is due to excitons, even when not visible at zero momentum.

The study uses Lanczos algorithm and analytical methods for different interaction regimes.

Abstract

The dynamical density-density correlation function is calculated for the one-dimensional, half-filled Hubbard model extended with nearest neighbor repulsion using the Lanczos algorithm for finite size systems and analytically for large on site repulsion compared to hopping amplitudes. At the zone boundary an excitonic feature exists for any finite nearest neighbor repulsion and exhausts most of the spectral weight, even for parameters where no exciton is visible at zero momentum.