Fluid transport properties by equilibrium molecular dynamics. I. Methodology at extreme fluid states

Citation
Dk. Dysthe et al., Fluid transport properties by equilibrium molecular dynamics. I. Methodology at extreme fluid states, J CHEM PHYS, 110(8), 1999, pp. 4047-4059
Citations number
34
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF CHEMICAL PHYSICS
ISSN journal
00219606 → ACNP
Volume
110
Issue
8
Year of publication
1999
Pages
4047 - 4059
Database
ISI
SICI code
0021-9606(19990222)110:8<4047:FTPBEM>2.0.ZU;2-A
Abstract
The Green-Kubo formalism for evaluating transport coefficients by molecular dynamics has been applied to flexible, multicenter models of linear and br anched alkanes in the gas phase and in the liquid phase from ambient condit ions to close to the triple point. The effects of integration time step, po tential cutoff and system size have been studied and shown to be small comp ared to the computational precision except for diffusion in gaseous n-butan e. The RATTLE algorithm is shown to give accurate transport coefficients fo r time steps up to a limit of 8 fs. The different relaxation mechanisms in the fluids have been studied and it is shown that the longest relaxation ti me of the system governs the statistical precision of the results. By measu ring the longest relaxation time of a system one can obtain a reliable erro r estimate from a single trajectory. The accuracy of the Green-Kubo method is shown to be as good as the precision for all states and models used in t his study even when the system relaxation time becomes very long. The effic iency of the method is shown to be comparable to nonequilibrium methods. Th e transport coefficients for two recently proposed potential models are pre sented, showing deviations from experiment of 0%-66%. (C) 1999 American Ins titute of Physics. [S0021-9606(99)50908-2].