Phase diagram of the hard-sphere potential model in three and four dimensions using a pseudo-hard-sphere potential

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Main Authors: Bedolla-Montiel, Edwin A., Castañeda-Cerdán, Ramón A., Castañeda-Priego, Ramón
Format: Preprint
Published: 2025
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author Bedolla-Montiel, Edwin A.
Castañeda-Cerdán, Ramón A.
Castañeda-Priego, Ramón
author_facet Bedolla-Montiel, Edwin A.
Castañeda-Cerdán, Ramón A.
Castañeda-Priego, Ramón
contents The hard-sphere potential has become a cornerstone in the study of both molecular and complex fluids. Despite its mathematical simplicity, its implementation in fixed time-step molecular simulations remains a formidable challenge due to the discontinuity at contact. To circumvent the issues associated with the ill-defined force at contact, a continuous potential--referred to here as the pseudo-hard-sphere (pHS) potential--has recently been proposed [J. Chem, Phys. 149, 164907 (2018)]. This potential is constructed to match the second virial coefficient of the hard-sphere potential and is expected to mimic its thermodynamic properties. However, this hypothesis has only been partially validated within the fluid region of the phase diagram for hard-sphere dispersions in two and three dimensions. In this contribution, we examine the ability of the continuous pHS potential to reproduce the equation of state of a hard-sphere fluid, not only in the fluid phase but also across the fluid-solid coexistence region. Our focus is primarily on hard-sphere systems in three and four dimensions. We compare the results obtained from Brownian dynamics simulations of the pHS potential with those derived from refined event-driven simulations of the corresponding hard-sphere potential. Furthermore, we provide a comparative analysis with theoretical equations of state based on both mean-field and integral equation approximations.
format Preprint
id arxiv_https___arxiv_org_abs_2502_03959
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Phase diagram of the hard-sphere potential model in three and four dimensions using a pseudo-hard-sphere potential
Bedolla-Montiel, Edwin A.
Castañeda-Cerdán, Ramón A.
Castañeda-Priego, Ramón
Soft Condensed Matter
The hard-sphere potential has become a cornerstone in the study of both molecular and complex fluids. Despite its mathematical simplicity, its implementation in fixed time-step molecular simulations remains a formidable challenge due to the discontinuity at contact. To circumvent the issues associated with the ill-defined force at contact, a continuous potential--referred to here as the pseudo-hard-sphere (pHS) potential--has recently been proposed [J. Chem, Phys. 149, 164907 (2018)]. This potential is constructed to match the second virial coefficient of the hard-sphere potential and is expected to mimic its thermodynamic properties. However, this hypothesis has only been partially validated within the fluid region of the phase diagram for hard-sphere dispersions in two and three dimensions. In this contribution, we examine the ability of the continuous pHS potential to reproduce the equation of state of a hard-sphere fluid, not only in the fluid phase but also across the fluid-solid coexistence region. Our focus is primarily on hard-sphere systems in three and four dimensions. We compare the results obtained from Brownian dynamics simulations of the pHS potential with those derived from refined event-driven simulations of the corresponding hard-sphere potential. Furthermore, we provide a comparative analysis with theoretical equations of state based on both mean-field and integral equation approximations.
title Phase diagram of the hard-sphere potential model in three and four dimensions using a pseudo-hard-sphere potential
topic Soft Condensed Matter
url https://arxiv.org/abs/2502.03959