SYSTEM-SIZE EFFECTS AT THE ISOTROPIC-NEMATIC TRANSITION FROM COMPUTER-SIMULATION

We present a computer-simulation study regarding the effect of system size on the isotropic-nematic transition in a molecular fluid model. Systems of 256, 500, and 864 molecules interacting through the Gay-Berne model are analyzed along an isotherm by using molecular dynamics in the NVT ensemble. For the three system sizes under consideration, the system exhibits a weak first-order isotropic-nematic transition. The transition densities are calculated by using thermodynamic integration. We find that the transition shifts to higher densities as the number of particles N increases. In addition, the transition weakens as N gets larger. These results are used to extract information on the transition properties in the infinite-system limit. The N dependence of thermodynamic properties are estimated from the simulation results and are compared with theoretical predictions.