Ground state properties of a dilute homogeneous Bose gas of hard disks in two dimensions

TL;DR

This paper investigates the ground state properties of a dilute two-dimensional Bose gas of hard disks using a variational approach, revealing deviations from low-density theories and analyzing condensate fractions.

Contribution

It introduces a variational many-body method to study 2D Bose gases, providing new insights into their energy, structure, and condensate fraction at low densities.

Findings

Deviations from low-density expansions at x~0.001

Condensate fraction lower in 2D than in 3D

Radial distribution function and density matrix behaviors analyzed

Abstract

The energy and structure of a dilute hard-disks Bose gas are studied in the framework of a variational many-body approach based on a Jastrow correlated ground state wave function. The asymptotic behaviors of the radial distribution function and the one-body density matrix are analyzed after solving the Euler equation obtained by a free minimization of the hypernetted chain energy functional. Our results show important deviations from those of the available low density expansions, already at gas parameter values $x\sim 0.001$. The condensate fraction in 2D is also computed and found generally lower than the 3D one at the same $x$.