TEMPERATURE-DEPENDENCE OF THE PROPERTIES OF SIMULATED PCH5

We present the results of molecular dynamics simulation studies of 4-( trans-4'-pentylcyclohexyl)benzonitrile (PCH5) at different temperature s in the isotropic and nematic phases within the united atom approach. Special attention is paid to the electrostatic interactions. Differen t methods of determining point charges are compared and the effect of the electrostatic interactions on the molecular distribution is consid ered. Their decisive influence on local molecular packing and phase tr ansition temperature is shown. We analyse various static and dynamic p roperties, being specially interested in the reliability of the simula tion results, to check to which extent they are distorted by the confi nements adopted during the simulations land 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, b ut also the relative dependence of the order parameters of various ran ks.