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
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].