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arXiv · 1102.0134

An Efficient Monte-Carlo Method for Calculating Free-Energy in Long-Range Interacting Systems

Kazuya Watanabe·Munetaka Sasaki
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Abstract

We present an efficient Monte-Carlo method for long-range interacting systems to calculate free energy as a function of an order parameter. In this method, a variant of the Wang-Landau method regarding the order parameter is combined with the stochastic cutoff method, which has recently been developed for long-range interacting systems. This method enables us to calculate free energy in long-range interacting systems with reasonable computational time despite the fact that no approximation is involved. This method is applied to a three-dimensional magnetic dipolar system to measure free energy as a function of magnetization. By using the present method, we can calculate free energy for a large system size of $16^3$ spins despite the presence of long-range magnetic dipolar interactions. We also discuss the merits and demerits of the present method in comparison with the conventional Wang-Landau method in which free energy is calculated from the joint density of states of energy and order parameter.

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Kazuya Watanabe, Munetaka Sasaki. 2011-08-26. An Efficient Monte-Carlo Method for Calculating Free-Energy in Long-Range Interacting Systems. https://doi.org/10.1143/jpsj.80.093001

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