Gutzwiller study of extended Hubbard models with fixed boson densities

TL;DR

This study explores the phase diagrams of extended Bose-Hubbard models at fixed boson densities, revealing conditions under which supersolid phases emerge and how transfer integral influences phase stability.

Contribution

It provides a comprehensive analysis of ground states, including supersolid phases, using Gutzwiller wave functions and linear programming, highlighting the impact of transfer integral on phase behavior.

Findings

Supersolid phases can be ground states at certain parameters.

Phase diagrams vary significantly with transfer integral.

Density differences correlate with boson density and transfer integral.

Abstract

We studied all possible ground states, including supersolid (SS) phases and phase separations of hard-core- and soft-core-extended Bose--Hubbard models with fixed boson densities by using the Gutzwiller variational wave function and the linear programming method. We found that the phase diagram of the soft-core model depends strongly on its transfer integral. Furthermore, for a large transfer integral, we showed that an SS phase can be the ground state even below or at half filling against the phase separation. We also found that the density difference between nearest-neighbor sites, which indicates the density order of the SS phase, depends strongly on the boson density and transfer integral.