Abstract
Computing phase diagrams of model systems is an essential part of computational condensed matter physics. In this paper, we discuss in detail the interface pinning (IP) method for calculation of the Gibbs free energy difference between a solid and a liquid. This is done in a single equilibrium simulation by applying a harmonic field that biases the system towards two-phase configurations. The Gibbs free energy difference between the phases is determined from the average force that the applied field exerts on the system. As a test system, we study the Lennard-Jones model. It is shown that the coexistence line can be computed efficiently to a high precision when the IP method is combined with the Newton-Raphson method for finding roots. Statistical and systematic errors are investigated. Advantages and drawbacks of the IP method are discussed. The high pressure part of the temperature-density coexistence region is outlined by isomorphs.
Highlights
The purpose of this paper is to give a detailed description of the interface pinning (IP) method and show that it is a viable way of computing the solid-liquid Gibbs free energy and construct phase diagrams
II, we describe the IP method in general terms
IV, the IP method is applied to the LJ model
Summary
The purpose of this paper is to give a detailed description of the IP method and show that it is a viable way of computing the solid-liquid Gibbs free energy and construct phase diagrams. The remainder of the paper is organized as follows. The coexistence line is computed by combining the IP method with the Newton-Raphson method for finding roots, and statistical and systematic errors are investigated. The paper is completed with a summary
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