Journal ArticleDOI
Role of Repulsive Forces in Determining the Equilibrium Structure of Simple Liquids
TLDR
In this paper, the Fourier transform of the pair correlation function is used to calculate the structure factor of a reference system in which the intermolecular forces are entirely repulsive and identical to the repulsive forces in a Lennard-Jones fluid.Abstract:
The different roles the attractive and repulsive forces play in forming the equilibrium structure of a Lennard‐Jones liquid are discussed. It is found that the effects of these forces are most easily separated by considering the structure factor (or equivalently, the Fourier transform of the pair‐correlation function) rather than the pair‐correlation function itself. At intermediate and large wave vectors, the repulsive forces dominate the quantitative behavior of the liquid structure factor. The attractions are manifested primarily in the small wave vector part of the structure factor; but this effect decreases as the density increases and is almost negligible at reduced densities higher than 0.65. These conclusions are established by considering the structure factor of a hypothetical reference system in which the intermolecular forces are entirely repulsive and identical to the repulsive forces in a Lennard‐Jones fluid. This reference system structure factor is calculated with the aid of a simple but accurate approximation described herein. The conclusions lead to a very simple prescription for calculating the radial distribution function of dense liquids which is more accurate than that obtained by any previously reported theory. The thermodynamic ramifications of the conclusions are presented in the form of calculations of the free energy, the internal energy (from the energy equation), and the pressure (from the virial equation). The implications of our conclusions to perturbation theories for liquids and to the interpretation of x‐ray scattering experiments are discussed.read more
Citations
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Journal ArticleDOI
CHARMM: the biomolecular simulation program.
Bernard R. Brooks,Charles L. Brooks,Alexander D. MacKerell,Lennart Nilsson,Robert J. Petrella,Benoît Roux,Youngdo Won,Georgios Archontis,Christian Bartels,Stefan Boresch,Amedeo Caflisch,Leo S. D. Caves,Qiang Cui,Aaron R. Dinner,Michael Feig,Stefan Fischer,Jiali Gao,Milan Hodošček,Wonpil Im,K. Kuczera,Themis Lazaridis,Jianpeng Ma,V. Ovchinnikov,Emanuele Paci,Richard W. Pastor,Carol Beth Post,Jingzhi Pu,M. Schaefer,Bruce Tidor,Richard M. Venable,H. L. Woodcock,Xiongwu Wu,Wei Yang,Darrin M. York,Martin Karplus,Martin Karplus +35 more
TL;DR: An overview of the CHARMM program as it exists today is provided with an emphasis on developments since the publication of the original CHARMM article in 1983.
Journal ArticleDOI
Update of the CHARMM All-Atom Additive Force Field for Lipids: Validation on Six Lipid Types
Jeffery B. Klauda,Richard M. Venable,J. Alfredo Freites,Joseph W. O’Connor,Douglas J. Tobias,Carlos Mondragon-Ramirez,Igor Vorobyov,Alexander D. MacKerell,Richard W. Pastor +8 more
TL;DR: The presented lipid FF is developed and applied to phospholipid bilayers with both choline and ethanolamine containing head groups and with both saturated and unsaturated aliphatic chains and is anticipated to be of utility for simulations of pure lipid systems as well as heterogeneous systems including membrane proteins.
Journal ArticleDOI
g_mmpbsa--a GROMACS tool for high-throughput MM-PBSA calculations.
TL;DR: A new tool, g_mmpbsa, which implements the MM-PBSA approach using subroutines written in-house or sourced from the GROMACS and APBS packages is described, and the calculated interaction energy of 37 structurally diverse HIV-1 protease inhibitor complexes is compared.
Journal ArticleDOI
The nature of the liquid-vapour interface and other topics in the statistical mechanics of non-uniform, classical fluids
TL;DR: In this paper, a new generalization of the linear theory of spinodal decomposition is formulated and by considering a "nearly uniform" fluid, some useful results for the long-wavelength behaviour of the liquid structure factor of various monatomic liquids are obtained.
Journal ArticleDOI
Structure and nanostructure in ionic liquids.
References
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Journal ArticleDOI
Computer "Experiments" on Classical Fluids. I. Thermodynamical Properties of Lennard-Jones Molecules
TL;DR: In this article, the equilibrium properties of a system of 864 particles interacting through a Lennard-Jones potential have been integrated for various values of the temperature and density, relative, generally, to a fluid state.
Journal ArticleDOI
Phase Transitions of the Lennard-Jones System
Jean-Pierre Hansen,Loup Verlet +1 more
TL;DR: In this paper, Monte Carlo computations have been performed in order to determine the phase transitions of a system of particles interacting through a Lennard-Jones potential, and an indirect determination of the phase transition of the hard-sphere gas is made which is essentially in agreement with the results of more direct calculations.
Journal ArticleDOI
Equation of State for Hard Spheres
TL;DR: In this paper, simple and exact expressions for the compressibility and pressure equations of state predicted by the Percus-Yevick equation for hard spheres were found for Wainwright and Alder.
Journal ArticleDOI
Computer "Experiments" on Classical Fluids. II. Equilibrium Correlation Functions
TL;DR: In this paper, equilibrium correlation functions for a dense classical fluid are obtained by integrating the equation of motion of a system of 864 particles interacting through a Lennard-Jones potential, and the behaviour of the correlation function at large distance and that of its Fourier transform at large wave number are discussed in detail and shown to be related to the existence of a strong repulsion in the potential.
Journal ArticleDOI
Seventh Virial Coefficients for Hard Spheres and Hard Disks
Francis H. Ree,William G. Hoover +1 more
TL;DR: In this paper, the authors used modified star integrals instead of the usual Mayer Star integrals to simplify the calculation of the seventh virial coefficient B7 and obtained the following values of B7: hard spheres, B7/(B2)6 = 0.0138±0.0004; hard disks, B 7/(B 2)6= 0.1141±0.0005; hard rods, hard disks and hard spheres.