A GENERALIZED GAUSSIAN OVERLAP MODEL FOR FLUIDS OF ANISOTROPIC PARTICLES

The Gaussian overlap model for anisotropic particles is generalized to include ellipsoids which are not axially symmetric. Explicit analytical expressions are given for the potential and for the torques necessary in molecular dynamics (MD) simulations. Employing this model, we have obtained MD results for several systems carefully selected to determine the influence of molecular biaxiality upon the formation of uniaxial nematic phases. By comparing systems of biaxial and axially symmetric particles with the same length-to-breadth ratio and at the same reduced density and temperature, it is clearly shown that even relatively little molecular "flatness" can significantly favor the formation of a uniaxial nematic phase. For example, ellipsoids characterized by the aspect ratios 2:3:9 form a stable nematic whereas the axially symmetric counterpart (i.e., 3:3:9) has no stable liquid crystal phase. © 1995 American Institute of Physics.