%0 Book Section %1 statphys23_1119 %A Lahiri, T.K. %A Singh, S. %B Abstract Book of the XXIII IUPAP International Conference on Statistical Physics %C Genova, Italy %D 2007 %E Pietronero, Luciano %E Loreto, Vittorio %E Zapperi, Stefano %K crystals general liquid phase statphys23 studies topic-7 transitions %T Statistical mechanical theory for discotic liquid crystal %U http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=1119 %X A Statistical mechanical theory is applied to study the equilibrium properties of discotic nematic liquid crystals. We are reporting our calculation for finding out the second long range orientational order parameter and various other thermodynamic properties of discotic nematic liquid crystals at the discotic nematic – isotropic transition (ND - I) on the basis of perturbation theory. We have considered in our theory a non polar liquid crystals in ND phase of the type (CnH2n+1) choosing by E. M. Aver’yanov 1 We have applied a perturbation expansion method 2 of a disc-shaped system to study a molecular description of the equilibrium properties of discotic nematogens. We assume that the disc shaped molecules are oblate ellipsoids of revolution parameterized by the length-width ratio which is less then one for oblate ellipsoids. We consider a model system (which simulates a discotic-nematic liquid crystal) in which molecules are assumed to interact via a pair potential having both repulsive and attractive parts. The repulsion part is represented by a repulsion between hard oblate ellipsoid of revolution and is short range, rapidly varying potential. The attractive potential, a function of center of mass distance and relative orientation between two molecules is represented by dispersion interaction. The properties of the reference system and first order perturbation term are evaluated using a decoupling approximation which decouples orientation from translational degrees of freedom. The fractional change in volume, transition entropy, sensitivity of the order parameter to volume change (at constant temperature) and the temperature change (at constant volume) etc., for suitably chosen potential parameters, is also analysed at the ND-I transition. The results show our theory demonstrate successfully the experimental result obtained by Averynov. References:\\ 1) Aver’yanov E. M., 1995, JETP Lett, 61, 815.\\ 2) Singh S and Singh Y, 1982, Mol.Cryst. Liq. Cryst., 87,211.

@incollection{statphys23_1119, abstract = {A Statistical mechanical theory is applied to study the equilibrium properties of discotic nematic liquid crystals. We are reporting our calculation for finding out the second long range orientational order parameter and various other thermodynamic properties of discotic nematic liquid crystals at the discotic nematic – isotropic transition (ND - I) on the basis of perturbation theory. We have considered in our theory a non polar liquid crystals in ND phase of the type (CnH2n+1) choosing by E. M. Aver’yanov \cite{1} We have applied a perturbation expansion method \cite{2} of a disc-shaped system to study a molecular description of the equilibrium properties of discotic nematogens. We assume that the disc shaped molecules are oblate ellipsoids of revolution parameterized by the length-width ratio which is less then one for oblate ellipsoids. We consider a model system (which simulates a discotic-nematic liquid crystal) in which molecules are assumed to interact via a pair potential having both repulsive and attractive parts. The repulsion part is represented by a repulsion between hard oblate ellipsoid of revolution and is short range, rapidly varying potential. The attractive potential, a function of center of mass distance and relative orientation between two molecules is represented by dispersion interaction. The properties of the reference system and first order perturbation term are evaluated using a decoupling approximation which decouples orientation from translational degrees of freedom. The fractional change in volume, transition entropy, sensitivity of the order parameter to volume change (at constant temperature) and the temperature change (at constant volume) etc., for suitably chosen potential parameters, is also analysed at the ND-I transition. The results show our theory demonstrate successfully the experimental result obtained by Averynov. References:\\ 1) Aver’yanov E. M., 1995, JETP Lett, 61, 815.\\ 2) Singh S and Singh Y, 1982, Mol.Cryst. Liq. Cryst., 87,211.}, added-at = {2007-06-20T10:16:09.000+0200}, address = {Genova, Italy}, author = {Lahiri, T.K. and Singh, S.}, biburl = {https://www.bibsonomy.org/bibtex/2fa96f9cdba13e1e6e3ba3bfe7f291fea/statphys23}, booktitle = {Abstract Book of the XXIII IUPAP International Conference on Statistical Physics}, editor = {Pietronero, Luciano and Loreto, Vittorio and Zapperi, Stefano}, interhash = {615f324e22fb468f2402b981e5343f9a}, intrahash = {fa96f9cdba13e1e6e3ba3bfe7f291fea}, keywords = {crystals general liquid phase statphys23 studies topic-7 transitions}, month = {9-13 July}, timestamp = {2007-06-20T10:16:39.000+0200}, title = {Statistical mechanical theory for discotic liquid crystal}, url = {http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=1119}, year = 2007 }