| | 1 | Author
| Prasad Durga, B. Ojha, V.G K M Raja Rajeswari, Pisipati | Requires cookie* | | | Title
| Molecular Ordering of a Nematic Liquid Crystal in a Dielectric Medium  | | | | Abstract
| A computational analysis of the molecular ordering of 4-(4'-ethoxyphenylazo) phenyl hexanoate (EPPH) has ben carried out on the basis of intermolecular interaction energy calculations. The CNDO/2 method has been employed to evaluate the net atomic charge ad atomic dipole moment components at each atomic centre of the molecule. A modified Rayleigh-Schrödinger perturbation theory alongwith a multicentered-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, and cor-responding probabilities have been calculated in a dielectric medium (benzene) using the Maxwell-Boltzmann formula. Further, the flexibility of various configurations has been studied in terms of vari-ations of the probability due to departure from the most probable configuration. All possible geometri-cal arrangements between molecular pairs have been considered during stacking, in-plane and terminal interactions, and the most favourable configuration of the paring has been obtained. It has been observed that in a dielectric medium the probabilities are redistributed and there is a considerable rise in the prob-ability of interactions although the order of preference remains the same. An attempt has been made to explain the nematogenic behaviour of liquid crystals and thereby develop a molecular model for liquid crystallinity. Results have been discussed in the light of those obtained for other nematogens like EPPV [4-(4'-ethoxyphenylazo) phenyl valerate] and DPAB [4-4'-di-n-propoxy-azoxybenzene], | | | |
Reference
| Z. Naturforsch. 55a, 929—935 (2000); received November 3 2000 | | | |
Published
| 2000 | | | |
Keywords
| CNDO/2 Method, Intermolecular Interactions, Statistical Analysis, Computer Simulation | | | |
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| default:Reihe_A/55/ZNA-2000-55a-0929.pdf | | | | Identifier
| ZNA-2000-55a-0929 | | | | Volume
| 55 | |
| 2 | Author
| DurgaPrasad Ojha | Requires cookie* | | | Title
| Molecular Ordering in Liquid Crystalline EMBAC. A Quantum Mechanical Study | | | | Abstract
| Molecular ordering in a liquid crystal, ethyl 4-(4'-methoxybenzylidene amino) cinnamate (EMBAC) has been studied by intermolecular interaction energy calculations. The CNDO/2 method has been employed to compute the atomic charge and atomic dipole at each atomic centre. The modified Rayleigh-Schrödinger perturbation theory along with the multicentered-multipole expansion method have been employed to evaluate the long-range intermolecular interactions, while a '6-exp' potential function has been assumed for the short-range interactions. On the basis of stacking, in-plane, and terminal interac-tion energy calculations all possible geometrical arrangements of a molecular pair have been considered, and the most favourable configuration of the pair has been obtained. Molecular parameters like total ener-gy, binding energy and total dipole moment have been given. Results are discussed in the light of those obtained for the nematogens 4-(4'-ethoxyphenylazo) phenyl valerate (EPPV) and 4,4'-di-n-propoxy-azoxybenzene (DPAB). An attempt is made to explain the liquid crystalline behavior of these liquid crys-tals and thereby develop a molecular model for liquid crystallinity. | | | |
Reference
| Z. Naturforsch. 55a, 923—928 (2000); received September 28 2000 | | | |
Published
| 2000 | | | |
Keywords
| Liquid Crystal, Multicentered-multipole, CNDO/2 Method, Intermolecular Interactions, EMBAC | | | |
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| default:Reihe_A/55/ZNA-2000-55a-0923.pdf | | | | Identifier
| ZNA-2000-55a-0923 | | | | Volume
| 55 | |
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