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'Computer Simulation' in keywords Facet   Publication Year 2001  [X]
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2001[X]
1Author    DurgaPrasad OjhaRequires cookie*
 Title    Nematogenic Behaviour of a Cyano-Compound Using Quantum Mechanics and Computer Simulations  
 Abstract    Using quantum mechanics and intermolecular forces, the molecular ordering of a nematogenic cya-no-compound, 5-(frans-4-ethylcyclohexyl)-2-(4-cyanophenyl)-pyrimidine (ECCPP), has been exam­ ined. The CNDO/2 method has been employed to evaluate the net atomic charge and the dipole mo­ ment components at each atomic centre of the molecule. The configuration energy has been computed using the modified Rayleigh-Schrödinger perturbation method at intervals o f 1Ä in translation and 10P in rotations, and corresponding probabilities have been calculated using Maxwell-Boltzmann statistics. The flexibility of various configurations has been studied in terms of the variation of the probability due to small departures from the most probable configuration. All possible geometrical arrangements between a molecular pair have been considered during stacking, in-plane and terminal interactions, and the most favourable configuration of pairing has been obtained. An attempt has been made to under­ stand the behaviour of the molecules in terms of their relative order. The results have been compared with those obtained for other nematogens like DPAB [4,4'-di-n-propoxy-azoxybenzene] and EMBAC [ethyl 4-(4'-methoxybenzylidene amino) cinnamate]. 
  Reference    Z. Naturforsch. 56a, 319—325 (2001); received February 6 2000 
  Published    2001 
  Keywords    ECCPP, CNDO/2 Method, Intermolecular Forces, Computer Simulation 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0319.pdf 
 Identifier    ZNA-2001-56a-0319 
 Volume    56 
2Author    Prasad Durga, Devesh Ojha, V.G K M Kumar, PisipatiRequires cookie*
 Title    Molecular Organization in a Nematogen: PBPCN -A Computational Analysis Based on Quantum Mechanics  
 Abstract    A computational analysis has been carried out to determine the configurational preference of a pair o f 4'-n-pentyloxy-4-biphenylcarbonitrile (PBPCN) molecules 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 centre of the molecule. Modified Rayleigh-Schrödinger perturbation theory along with 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. On the basis of stacking, in-plane and terminal interaction energy calculations, all possible geometrical arrangements o f molecular pair have been considered. It has been observed that the molecule has a strong preference for stacking through a particular face, while the other configurations, such as stacking through the other face, in-plane and terminal interactions show, in general, an aligned structure along molecular axis. The results are discussed in the light o f experimental as well as other theoretical observations. 
  Reference    Z. Naturforsch. 56a, 730—734 (2001); received September 7 2001 
  Published    2001 
  Keywords    PBPCN, Nematogen, Interaction Energy, Computer Simulation 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0730.pdf 
 Identifier    ZNA-2001-56a-0730 
 Volume    56 
3Author    Prasad Durga, Devesh Ojha, V.G K M Kumar, PisipatiRequires cookie*
 Title    Smectogenic Behaviour of 70.6 at it's Phase Transition Temperature: A Computational Analysis Reprint request to  
 Abstract    A computational analysis has been carried out to determine the configurational preference of a pair of Ar-(4-n-heptyloxybenzylidine)-4-hexylaniline (70.6) molecules with respect to translatory and orien­ tational motions. The CNDO/2 method has been employed to evaluate the net atomic charge and atom­ ic dipole components at each atomic centre of the molecule. The configurational energy has been com­ puted using the modified Rayleigh-Schrödinger perturbation method. The obtained energies were used to calculate the probability of each configuration at phase transition temperature, using Maxwell-Boltz-mann's formula. The flexibility of various configurations has been studied in terms o f variations of the probability due to small departures from the most probable configuration. The results are discussed in the light of experimental as well as other theoretical observations. The smectogenic character of the molecule has been correlated with the parameters introduced in this paper. 
  Reference    Z. Naturforsch. 56a, 873—878 (2001); received October 12 2001 
  Published    2001 
  Keywords    706, CNDO/2 Method, Quantum Chemistry, Computer Simulation 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0873.pdf 
 Identifier    ZNA-2001-56a-0873 
 Volume    56