Radial Distribution Function in a Two Dimensional Core-Shoulder Particle System

Fuente: arXiv
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Autori principali: Wassermair, Michael, Kahl, Gerhard, Archer, Andrew J, Roth, Roland
Natura: Preprint
Pubblicazione: 2026
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author Wassermair, Michael
Kahl, Gerhard
Archer, Andrew J
Roth, Roland
author_facet Wassermair, Michael
Kahl, Gerhard
Archer, Andrew J
Roth, Roland
contents An important quantity in liquid state theory is the radial distribution function $g(r)$. It can be calculated within the framework of classical density functional theory in two very distinct ways. In the test-particle route, one fixes a single fluid particle, turning it into an external potential in which the inhomogeneous structure of the fluid is calculated by minimising the functional. The second route to $g(r)$ in density functional theory employs the Ornstein-Zernike equation and the pair direct correlation function, that can be obtained from the second functional derivatives of the excess free energy functional. Since typically an approximate excess free energy functional is employed, one generally expects that the test-particle route, which requires only one functional derivative, to be more accurate than the Ornstein-Zernike route. Here we study a two dimensional core-shoulder particle system and present results that challenge this expectation. Our results show that in this system test-particle results for $g(r)$ are not always better than results obtained via the Ornstein-Zernike route.
format Preprint
id arxiv_https___arxiv_org_abs_2603_24537
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Radial Distribution Function in a Two Dimensional Core-Shoulder Particle System
Wassermair, Michael
Kahl, Gerhard
Archer, Andrew J
Roth, Roland
Soft Condensed Matter
Statistical Mechanics
An important quantity in liquid state theory is the radial distribution function $g(r)$. It can be calculated within the framework of classical density functional theory in two very distinct ways. In the test-particle route, one fixes a single fluid particle, turning it into an external potential in which the inhomogeneous structure of the fluid is calculated by minimising the functional. The second route to $g(r)$ in density functional theory employs the Ornstein-Zernike equation and the pair direct correlation function, that can be obtained from the second functional derivatives of the excess free energy functional. Since typically an approximate excess free energy functional is employed, one generally expects that the test-particle route, which requires only one functional derivative, to be more accurate than the Ornstein-Zernike route. Here we study a two dimensional core-shoulder particle system and present results that challenge this expectation. Our results show that in this system test-particle results for $g(r)$ are not always better than results obtained via the Ornstein-Zernike route.
title Radial Distribution Function in a Two Dimensional Core-Shoulder Particle System
topic Soft Condensed Matter
Statistical Mechanics
url https://arxiv.org/abs/2603.24537