Ground-state phase diagram of a half-filled one-dimensional extended Hubbard model

TL;DR

This study maps the phase diagram of a half-filled one-dimensional extended Hubbard model using density-matrix renormalization group, revealing critical lines, phase transitions, and a bond-order-wave phase induced by spin coupling.

Contribution

It provides a detailed phase diagram of the extended Hubbard model, identifying the nature of phase transitions and the emergence of a bond-order-wave phase.

Findings

Critical line V_c(U) ≈ U/2 separates Mott and charge-density-wave phases.

Transition changes from continuous to first order at a tricritical point U_t=3.7t, V_t=2t.

Bond-order-wave phase appears on the critical line for U between U_t and 7-8t.

Abstract

The density-matrix renormalization group is used to study the phase diagram of the one-dimensional half-filled Hubbard model with on-site (U) and nearest-neighbor (V) repulsion, and hopping t. A critical line V_c(U) approximately equal to U/2 separates a Mott insulating phase from a charge-density-wave phase. The formation of bound charge excitations for V > 2t changes the phase transition from continuous to first order at a tricritical point U_t = 3.7t, V_t=2t. A frustrating effective antiferromagnetic spin coupling induces a bond-order-wave phase on the critical line V_c(U) for U_t < U < 7-8 t.