Molecular Crystals and Liquid Crystals, Vol.378, 147-156, 2002
Ordering in homologous series of 4-cyano-4'-alkylbiphenyls(nCB) - A statistical study
A comparative study of molecular ordering in three homologous series of 4-cyano-4'-alkylbiphenyls (nCB) with alkyl groups pentyl (5CB) , hexyl (6CB) , and heptyl (7CB) have been carried out with respect to translatory and orientational motions. The CNDO/2 method has been employed to evaluate the net atomic charge and atomic dipole components at each atomic center of the molecule. Modified Rayleigh-Schrodinger perturbation theory along with multicentered-multipole expansion method has been employed to evaluate the long-range intermolecular interactions, while a 6-exp potential function has been assumed for short-range interactions. The total interaction energy values obtained through these computations were used to calculate the probability of each configuration at room temperature using Maxwell-Boltzmann formula. On the basis of stacking, in-plane, and terminal interaction energy calculations, all possible geometrical arrangements of molecular pair have been considered, and the most favorable configuration of pairing has been obtained among the compounds. An attempt has been made to develop a molecular model for liquid crystalline molecules.