A Monte Carlo study of the triangular lattice gas with the first- and the second-neighbor exclusions

TL;DR

This study uses a Monte Carlo approach to analyze a triangular lattice gas with exclusions, confirming its universality class and identifying potential logarithmic corrections affecting thermal exponents.

Contribution

It introduces a Swendsen-Wang-like cluster algorithm for the lattice gas and provides detailed finite-size scaling analysis of critical properties.

Findings

Critical chemical potential μ_c=1.75682(2)

Critical density ρ_c=0.180(4)

Supports 4-state Potts universality class

Abstract

We formulate a Swendsen-Wang-like version of the geometric cluster algorithm. As an application,we study the hard-core lattice gas on the triangular lattice with the first- and the second-neighbor exclusions. The data are analyzed by finite-size scaling, but the possible existence of logarithmic corrections is not considered due to the limited data. We determine the critical chemical potential as $\mu_c=1.75682 (2)$ and the critical particle density as $\rho_c=0.180(4)$. The thermal and magnetic exponents $y_t=1.51(1) \approx 3/2$ and $y_h=1.8748 (8) \approx 15/8$, estimated from Binder ratio $Q$ and susceptibility $\chi$, strongly support the general belief that the model is in the 4-state Potts universality class. On the other hand, the analyses of energy-like quantities yield the thermal exponent $y_t$ ranging from $1.440(5)$ to $1.470(5)$. These values differ significantly from the expected value 3/2, and thus imply the existence of logarithmic corrections.