Modelling the structure of chain-molecule liquids: a computer simulation of the n-alcanes C8-C30

Computer models of a series of liquid n-alkanes were generated, allowing for continuous variation of torsion angles and of atomic positions. Torsional and intramolecular and intermolecular nonbonded potentials were introduced. Calculated fractions of gauche bonds are slightly higher than those calculated from a rotational isomeric state model. No directional correlation between chains is found, except at very short distances. Calculated end-to-end distances and radii of gyration indicate random coil conformations. These results are unaffected by extension of the range of interaction to the attractive region and by variations of temperature and density.