The interface tension in the improved Blume-Capel model

TL;DR

This paper investigates the interface tension in the improved Blume-Capel model using efficient computational methods, confirming universality by comparing results with the 3D Ising model.

Contribution

It introduces a variance reduced estimator based on the exchange cluster algorithm to compute interface free energy and tension in the Blume-Capel model.

Findings

Universal amplitude ratios are precisely determined.

Results are consistent with the 3D Ising model.

Confirms universality hypothesis for the model.

Abstract

We study interfaces with periodic boundary conditions in the low temperature phase of the improved Blume-Capel model on the simple cubic lattice. The interface free energy is defined by the difference of the free energy of a system with anti-periodic boundary conditions in one of the directions and that of a system with periodic boundary conditions in all directions. It is obtained by integration of differences of the corresponding internal energies over the inverse temperature. These differences can be computed efficiently by using a variance reduced estimator that is based on the exchange cluster algorithm. The interface tension is obtained from the interface free energy by using predictions based on effective interface models. By using our numerical results for the interface tension $\sigma$ and the correlation length $\xi$ obtained in previous work, we determine the universal amplitude ratios $R_{2nd,+} = \sigma_0 f_{2nd,+}^2= 0.3863(6)$, $R_{2nd,-} = \sigma_0 f_{2nd,-}^2= 0.1028(1) $ and $R_{exp,-}=\sigma_0 f_{exp,-}^2= 0.1077(3)$. Our results are consistent with those obtained previously for the three-dimensional Ising model, confirming the universality hypothesis.