Molecular biaxiality and reorientational correlation functions in nematic phases: Theory.

Abstract

The molecular reorientation in nematic phases formed by rigid molecules with arbitrary shape is considered theoretically. In the framework of the small-step rotational diffusion model, the orientational correlation functions are obtained as fast converging series of exponentials. For cylindrical molecules our solutions are reduced to the results already reported in the literature. For molecules with effective ${D}_{2h}$ symmetry we demonstrate that at reasonable values of the order parameter 〈${D}_{02}^{2}$〉 the influence of the biaxiality on some correlation functions is significant and cannot be neglected.