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Crystal Research and Technology |
Cryst. Res. Technol. 40,
672 (2005) - Abstract -
Role of dielectric medium on mesogenic compounds (BCHs) at phase transition temperature: A comparative computational analysis
D. P. Ojha
Centre for Liquid Crystal Research and Education, Faculty of Physical Sciences, Acharya Nagarjuna University, Nagarjuna Nagar -522 510,A.P., India
A comparative computational analysis on two liquid crystalline disubstituted biphenylcyclohexanes (BCHs) of general formula R-C6H10-C6H4-X with R: C3H7; X: H (BCH30) and R: C5H11; X: CN (BCH5CN) has been carried out on the basis of quantum mechanics and intermolecular forces. The evaluation of atomic charge and dipole moment at each atomic centre has been carried out through an all-valence electron (CNDO/2) method. The configurational energy has been computed using the Rayleigh-Schrodinger perturbation method. The total interaction energy values obtained were used to calculate the probability of each configuration in dielectric medium (i.e. non-interacting and non-mesogenic solvent, benzene) at room temperature, transition temperature and above transition temperature using the Maxwell-Boltzmann’s formula. The flexibility of various interacting configurations has been studied in terms of variation of probability due to small departures from the most probable configurations. Further, the various possible geometrical arrangements between a molecular pair during the different modes of interactions have been considered. An attempt has been made to develop a new and interesting model for mesogenic compounds in a dielectric medium.
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