dorsal/arxiv
View SchemaPressure Calculation in Polar and Charged Systems using Ewald Summation: Results for the Extended Simple Point Charge Model of Water
| Authors | Gerhard Hummer, Niels Grønbech-Jensen, Martin Neumann |
|---|---|
| Categories | |
| ArXiv ID | physics/9806038 |
| URL | https://arxiv.org/abs/physics/9806038 |
| DOI | 10.1063/1.476834 |
| Journal | J. Chem. Phys. 109, 2791-2797, 1998 |
Abstract
Ewald summation and physically equivalent methods such as particle-mesh Ewald, kubic-harmonic expansions, or Lekner sums are commonly used to calculate long-range electrostatic interactions in computer simulations of polar and charged substances. The calculation of pressures in such systems is investigated. We find that the virial and thermodynamic pressures differ because of the explicit volume dependence of the effective, resummed Ewald potential. The thermodynamic pressure, obtained from the volume derivative of the Helmholtz free energy, can be expressed easily for both ionic and rigid molecular systems. For a system of rigid molecules, the electrostatic energy and the forces at the atom positions are required, both of which are readily available in molecular dynamics codes. We then calculate the virial and thermodynamic pressures for the extended simple point charge (SPC/E) water model at standard conditions. We find that the thermodynamic pressure exhibits considerably less system size dependence than the virial pressure. From an analysis of the cross correlation between the virial and thermodynamic pressure, we conclude that the thermodynamic pressure should be used to drive volume fluctuations in constant-pressure simulations.
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"abstract": "Ewald summation and physically equivalent methods such as particle-mesh\nEwald, kubic-harmonic expansions, or Lekner sums are commonly used to calculate\nlong-range electrostatic interactions in computer simulations of polar and\ncharged substances. The calculation of pressures in such systems is\ninvestigated. We find that the virial and thermodynamic pressures differ\nbecause of the explicit volume dependence of the effective, resummed Ewald\npotential. The thermodynamic pressure, obtained from the volume derivative of\nthe Helmholtz free energy, can be expressed easily for both ionic and rigid\nmolecular systems. For a system of rigid molecules, the electrostatic energy\nand the forces at the atom positions are required, both of which are readily\navailable in molecular dynamics codes. We then calculate the virial and\nthermodynamic pressures for the extended simple point charge (SPC/E) water\nmodel at standard conditions. We find that the thermodynamic pressure exhibits\nconsiderably less system size dependence than the virial pressure. From an\nanalysis of the cross correlation between the virial and thermodynamic\npressure, we conclude that the thermodynamic pressure should be used to drive\nvolume fluctuations in constant-pressure simulations.",
"arxiv_id": "physics/9806038",
"authors": [
"Gerhard Hummer",
"Niels Gr\u00f8nbech-Jensen",
"Martin Neumann"
],
"categories": [
"physics.chem-ph",
"cond-mat.soft",
"cond-mat.stat-mech",
"physics.comp-ph"
],
"doi": "10.1063/1.476834",
"journal_ref": "J. Chem. Phys. 109, 2791-2797, 1998",
"title": "Pressure Calculation in Polar and Charged Systems using Ewald Summation: Results for the Extended Simple Point Charge Model of Water",
"url": "https://arxiv.org/abs/physics/9806038"
},
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