Temperature dependence of the properties of simulated PCH5

Abstract

We present the results of molecular dynamics simulation studies of 4-(trans-4'-pentylcyclohexyl)- benzonitrile (PCH5) at different temperatures in the isotropic and nematic phases within the united atom approach. Special attention is paid to the electrostatic interactions. Different methods of determining point charges are compared and the effect of the electrostatic interactions on the molecular distribution is considered. Their decisive influence on local molecular packing and phase transition temperature is shown. We analyse various static and dynamic properties, being specially interested in the reliability of the simulation results, to check to which extent they are distorted by the confinements adopted during the simulations (and especially the size of the system). Using realistic molecular interaction models in contrast to simple model ellipsoids, we find that the number of molecules and the lengths of the simulation runs have to be increased considerably when studying macroscopic properties like the phase transition temperature and the order parameter. Much easier to access are single particle and local properties such as translational dynamics and local ordering, but also the relative dependence of the order parameters of various ranks.