A simple and accurate method to determine fluid-crystal phase boundaries from direct coexistence simulations

Fuente: arXiv
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Hauptverfasser: Smallenburg, Frank, Del Monte, Giovanni, de Jager, Marjolein, Filion, Laura
Format: Preprint
Veröffentlicht: 2024
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author Smallenburg, Frank
Del Monte, Giovanni
de Jager, Marjolein
Filion, Laura
author_facet Smallenburg, Frank
Del Monte, Giovanni
de Jager, Marjolein
Filion, Laura
contents One method for computationally determining phase boundaries is to explicitly simulate a direct coexistence between the two phases of interest. Although this approach works very well for fluid-fluid coexistences, it is often considered to be less useful for fluid-crystal transitions, as additional care must be taken to prevent the simulation boundaries from imposing unwanted strains on the crystal phase. Here, we present a simple adaptation to the direct coexistence method that nonetheless allows us to obtain highly accurate predictions of fluid-crystal coexistence conditions, assuming a fluid-crystal interface can be readily simulated. We test our approach on hard spheres, the screened Coulomb potential, and a 2D patchy-particle model. In all cases, we find excellent agreement between the direct coexistence approach and (much more cumbersome) free-energy calculation methods. Moreover, the method is sufficiently accurate to resolve the (tiny) free-energy difference between the face-centered cubic and hexagonally close-packed crystal of hard spheres in the thermodynamic limit. The simplicity of this method also ensures that it can be trivially implemented in essentially any simulation method or package. Hence, this approach provides an excellent alternative to free-energy based methods for the precise determination of phase boundaries.
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id arxiv_https___arxiv_org_abs_2403_10891
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publishDate 2024
record_format arxiv
spellingShingle A simple and accurate method to determine fluid-crystal phase boundaries from direct coexistence simulations
Smallenburg, Frank
Del Monte, Giovanni
de Jager, Marjolein
Filion, Laura
Soft Condensed Matter
Statistical Mechanics
One method for computationally determining phase boundaries is to explicitly simulate a direct coexistence between the two phases of interest. Although this approach works very well for fluid-fluid coexistences, it is often considered to be less useful for fluid-crystal transitions, as additional care must be taken to prevent the simulation boundaries from imposing unwanted strains on the crystal phase. Here, we present a simple adaptation to the direct coexistence method that nonetheless allows us to obtain highly accurate predictions of fluid-crystal coexistence conditions, assuming a fluid-crystal interface can be readily simulated. We test our approach on hard spheres, the screened Coulomb potential, and a 2D patchy-particle model. In all cases, we find excellent agreement between the direct coexistence approach and (much more cumbersome) free-energy calculation methods. Moreover, the method is sufficiently accurate to resolve the (tiny) free-energy difference between the face-centered cubic and hexagonally close-packed crystal of hard spheres in the thermodynamic limit. The simplicity of this method also ensures that it can be trivially implemented in essentially any simulation method or package. Hence, this approach provides an excellent alternative to free-energy based methods for the precise determination of phase boundaries.
title A simple and accurate method to determine fluid-crystal phase boundaries from direct coexistence simulations
topic Soft Condensed Matter
Statistical Mechanics
url https://arxiv.org/abs/2403.10891