RESUMO
A rigorous microscopic treatment of a nematic fluid system based on a pairwise interaction potential is immensely complex. For studying such systems molecular field theories are often the standard method of choice. In this paper we have chosen a simple effective potential U=u_{4}/v^{4}-u_{2}/v^{2}-Au_{2}/v^{2}ãP_{2}ãP_{2}(cosÏ) to study an isothermal-isobaric ensemble describing a liquid crystalline system. Using this we have studied in particular the pressure dependence of liquid crystalline phase transitions.
RESUMO
Extensive Monte Carlo simulations are performed to investigate the critical properties of a special singular point usually known as the Landau point. The singular behavior is studied in the case when the order parameter is a tensor of rank 2. Such an order parameter is associated with a nematic-liquid-crystal phase. A three-dimensional lattice dispersion model that exhibits a direct biaxial nematic-to-isotropic phase transition at the Landau point is thus chosen for the present study. Finite-size scaling and cumulant methods are used to obtain precise values of the critical exponent ν=0.713(4), the ratio γ/ν=1.85(1), and the fourth-order critical Binder cumulant U^{*}=0.6360(1). Estimated values of the exponents are in good agreement with renormalization-group predictions.