Rheology of liquid n-triacontane: Molecular dynamics simulation

Abstract

Molecular dynamics is applied to calculate diffusion coefficients of n-triacontane C30H62 using Einstein-Smoluchowski and Green-Kubo relations. The displacement Δr2(t) has a subdiffusive part Δr2 ∼ t α, caused by molecular crowding at low temperatures. Longtime asymptotes of v(0)v(t) are collated with the hydrodynamic tail t-3/2 demonstrated for atomic liquids. The influence of these asymptotes on the compliance of Einstein-Smoluchowski and Green-Kubo methods is analyzed. The effects of the force field parameters on the diffusion process are treated. The results are compared with experimental data.