A Comprehensive Study of Alkane Nonbonded Empirical Force Fields. Suggestions for Improved Parameter Sets

Molecular dynamics simulation of the CH4 and CH4–H2O systems up to 10GPa and 2573K

“…Many molecular potential models have been proposed for the investigation of the thermodynamic properties of CH 4 (Williams, 1967;Fitzwater and Bartell, 1976;Murad and Gubbins, 1978;Righini et al, 1981;Meinander and Tabisz, 1983;Jorgensen et al, 1984;Schoen et al, 1986;Saager and Fischer, 1990;Schindler et al, 1993;Kaminski et al, 1994;Nagy et al, 1995;Errington et al, 1998). Stassen (1999) reviewed the performance of most of the potential models and found that the simple one site LJ model played the best in the PVT property predictions.…”

Thermodynamic, Structural and Transport Properties of Lennard-Jones Liquid Systems. A Molecular Dynamics Simulations of Liquid Helium, Neon, Methane and Nitrogen

“…For liquid neon, several simulations involving different approaches were performed: Path-Integral Monte-Carlo (PIMC) [23,24], Path-Integral Brownian Dynamics (PIBD) [24], Monte-Carlo simulations using two effective pair potentials arising from Path-Integral formalism, the quadratic Feynmann-Hibbs(QFH), the Gaussian Feynmann-Hibbs (GFH) and the perturbation theory [25]. These works focused mainly on the radial distribution function for a complete structural investigation of these liquids, and recent calculations [3,21,22], taking into account quantum effects, cover only some state points of the phase diagram and offer no way to approach the transport properties accurately. In this work, we propose a complete study over 22 state points and most structural, thermodynamic and transport properties are studied.…”

Ab initiomethane dimer intermolecular potentials

“…Since the SCF procedure accounts for only the zero and first order contributions, which consists of exchange repulsion, electrostatic, and various deformation terms [28], a post-SCF method is necessary to evaluate the dispersion energy, which is the main contributor to the correlation energy in the methane dimer [28][29][30]. No analytical methanemethane potential parameters have been determined to date based on purely theoretical methods, except for our previous effort [31] to fit analytical potentials to the 31 dimer energies computed by Szczg~niak et al using the second-order Moller-Plesset perturbation (MP2) procedure [28]. Since the resultant analytical potentials have been found unsatisfactory, it has been concluded that either the medium size basis set used in that study [28] does not capture a sufficient part of the correlation energy, or the 31 energy points provide an inefficient sampling of the potential energy surface (PES) [31].…”

“…No analytical methanemethane potential parameters have been determined to date based on purely theoretical methods, except for our previous effort [31] to fit analytical potentials to the 31 dimer energies computed by Szczg~niak et al using the second-order Moller-Plesset perturbation (MP2) procedure [28]. Since the resultant analytical potentials have been found unsatisfactory, it has been concluded that either the medium size basis set used in that study [28] does not capture a sufficient part of the correlation energy, or the 31 energy points provide an inefficient sampling of the potential energy surface (PES) [31].…”

“…This procedure was necessary since currently it is beyond our capability to compute MP2 energies in a large basis for over a hundred configurations. The MM3 potential function [8], possessing a very flexible twoparameter potential form [31], has been reparameterized according to various criteria to fit MP2 and MP2 .... energies, MP2 forces, and the combination thereof. The two most successful parameter sets have been used subsequently to compute several properties, thereby evaluating their usefulness.…”