Ground state phases of the Half-Filled One-Dimensional Extended Hubbard Model

TL;DR

This paper maps out the ground state phases of the one-dimensional extended Hubbard model at half-filling, revealing how spin frustration and interaction strengths influence phase transitions between dimerized and charge-density-wave states.

Contribution

It provides a comprehensive phase diagram using quantum Monte Carlo, strong-coupling expansion, and Luttinger liquid theory, highlighting the role of spin frustration in stabilizing specific phases.

Findings

Spin frustration stabilizes a bond-ordered (dimerized) state.

Transition from dimerized to charge-density-wave state varies from continuous to first-order.

Phase boundaries depend on the ratio of U and V, with critical U around 5.5.

Abstract

Using quantum Monte Carlo simulations, results of a strong-coupling expansion, and Luttinger liquid theory, we determine quantitatively the ground state phase diagram of the one-dimensional extended Hubbard model with on-site and nearest-neighbor repulsions U and V. We show that spin frustration stabilizes a bond-ordered (dimerized) state for U appr. V/2 up to U/t appr. 9, where t is the nearest-neighbor hopping. The transition from the dimerized state to the staggered charge-density-wave state for large V/U is continuous for U up to appr. 5.5 and first-order for higher U.