Magnetic-field-induced weak order in nematic liquid crystals formed by biaxial molecules

Nematic liquid crystal system of interacting biaxial particles via dispersi on, forces is studied. The molecular orienting potential form in a magnetic field is given for the first time. Weakly ordered isotropic,ic phase is tr eated in the two-particle cluster approximation. Taking account of the mole cular biaxiality, it is found that the ratio of the lowest supercooling tem perature T* to the nematic-isotropic phase transition temperature T-C appro aches the observed value, and the validity of the mean field theory is clar ified.