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Orientational relaxation in a discotic liquid crystal

Chakrabarti, Dwaipayan and Jana, Biman and Bagchi, Biman (2007) Orientational relaxation in a discotic liquid crystal. In: Physical Review E, 75 (6). 061703-1-061703-7.

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Abstract

We investigate orientational relaxation of a model discotic liquid crystal, consisting of disclike molecules, by molecular dynamics simulations along two isobars starting from the high temperature isotropic phase. The two isobars have been so chosen that (a) the phase sequence isotropic- (I-) nematic- (N-) columnar (C) appears upon cooling along one of them and (b) the sequence isotropic- (I-) columnar- (C) along the other. While the orientational relaxation in the isotropic phase near the I-N phase transition in system (a) shows a power law decay at short to intermediate times, such power law relaxation is not observed in the isotropic phase near the I-C phase boundary in system (b). In order to understand this difference (the existence or the absence of the power law decay), we calculated the growth of the orientational pair distribution functions (OPDFs) near the I-N phase boundary and also near the I-C phase boundary. We find that the OPDF shows (a) marked growth in long range correlation as the I-N phase boundary is approached in the I-N-C system a, but such a growth is absent in the I-C system, which appears to be consistent with the result that I-N phase transition in the former is weakly first order while the I-C phase transition in the latter is not weak. As the system settles into the nematic phase, the decay of the single-particle second-rank orientational time correlation function follows a pattern that is similar to what is observed with calamitic liquid crystals and supercooled molecular liquids.

Item Type: Journal Article
Additional Information: Copyright of this artice belongs to The American Physical Society.
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited: 21 Sep 2007
Last Modified: 19 Sep 2010 04:39
URI: http://eprints.iisc.ernet.in/id/eprint/11879

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