CALCULATION OF THE THERMODYNAMIC FUNCTION OF SOME LIQUID-CRYSTALS BY THE MONTE-CARLO METHOD

The Monte-Carlo method in the canonical NVT-ensemble is used to consider a system of 64 ellipsoidal, interacting particles (molecules). Their interactions are calculated, using the modified Lennard-Jones potential. The calculations were performed in a parallelepipedic box, using periodic boundary conditions. The particle eccentricity (length-to-width ratio), necessary for calculations, was selected in accordance with the data of conformational analysis of such nematic liquid crystal molecules as 4-cyanphenyl ether n-heptylbenzoic acid and 4-n-butyl-4'-n'-heptanoil-oxiazoxibenzene. Similar calculations have been also performed for the case when each of the ensemble particles is presented as a cluster of several molecules. The interaction among them has been also calculated by the Lennard-Jones potential. Here ellipsoidal particle dimensions have been determined due to the data on the position of molecules inside the cluster, obtained by the method of atom-atom potentials. We have considered clusters consisting of two and four molecules. It is shown that the short-range order effects taken into account affect and specify the results for the specific heat and the order parameter.