A molecular dynamics study of chain configurations in n-alkane-like liquids

Abstract

We present precise measurements of the configurational properties of n-alkane-like liquids with 4, 5, 8, 20, 50, and 100 methylene groups. Quantities measured include the distributions of square radii of gyration, square end-to-end distances and proportion of conformers. To achieve high precision for n=50 and 100 a Fujitsu AP 1000 massively parallel processing machine with up to 512 processors is used. The results are compared with those obtained for the Flory model of alkane chains in which only correlation between nearest-neighbor torsion angles are considered; the latter were obtained by Monte Carlo sampling of isolated chains using the pivot algorithm. Discrepancies between the two sets of data are discussed in terms of solvent and end effects. For n=100 full configurational relaxation was not observed within 2 ns.

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