Computer simulation of ordering in bipolar nematogen H6CBP at phase transition temperature

The molecular ordering of 4-(6-hydroxyhexyloxy)-4′-cyanobiphenyl (H6CBP), a bipolar nematogen, has been carried out at nematic-isotropic transition temperature with respect to translatory and orientational motions. The complete neglect differential overlap (CNDO/2) method has been employed to compute the net atomic charge and atomic dipole moment at each atomic centre. The modified Rayleigh-Schrodinger perturbation theory with multicentred-multipole expansion method has been employed to evaluate long-range intermolecular interactions, while a 6-exp potential function has been assumed for short-range interactions. The interaction energy values obtained through these computations were used to calculate the probability of each configuration at nematic-isotropic transition temperature using the Maxwell-Boltzmann formula. On the basis of stacking, in-plane, and terminal interactions energy calculations, all possible geometrical arrangements of the molecular pair have been considered. The results are correlated with molecular parameters introduced in this article, and an attempt has been made to explain the nematic behaviour of the compound in terms of their relative order.