Molecular Vibration Approach to Polarizabilities of Methyl Cinnamate Liquid Crystal Compounds

A new theoretical method of evaluating polarizabilities of liquid crystals is presented and applied to the liquid crystalline compounds, namely n-alkyl-p-(4-ethoxy benzylidene amino)-α-methyl cinnamates, which exhibit smectic A and nematic phases. In the present method, vibrational frequencies are used to evaluate force constants, mean amplitude of vibration and hence bond polarizabilities. From mean polarizabilities, polarizability anisotropies and mean diamagnetic susceptibilities are also estimated. A close agreement is found between the values estimated from the present molecular vibration method and the reported data, which confirms the applicability of this method to the liquid crystals exhibiting smectic A and nematic phases. In addition, the variation of the order parameter with temperature is also studied.