Molecular structure and elastic properties of thermotropic liquid crystals: Integrated molecular dynamics-Statistical mechanical theory vs molecular field approach

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dc.contributor.authorCapar, M. Ilk
dc.contributor.authorNar, A.
dc.contributor.authorFerrarini, A.
dc.contributor.authorFrezza, E.
dc.contributor.authorGreco, C.
dc.contributor.authorZakharov, A. V.
dc.contributor.authorVakulenko, A. A.
dc.date.accessioned2019-10-27T21:52:41Z
dc.date.available2019-10-27T21:52:41Z
dc.date.issued2013
dc.departmentEge Üniversitesien_US
dc.description.abstractThe connection between the molecular structure of liquid crystals and their elastic properties, which control the director deformations relevant for electro-optic applications, remains a challenging objective for theories and computations. Here, we compare two methods that have been proposed to this purpose, both characterized by a detailed molecular level description. One is an integrated molecular dynamics-statistical mechanical approach, where the bulk elastic constants of nematics are calculated from the direct correlation function (DCFs) and the single molecule orientational distribution function [D. A. McQuarrie, Statistical Mechanics (Harper & Row, New York, 1973)]. The latter is obtained from atomistic molecular dynamics trajectories, together with the radial distribution function, from which the DCF is then determined by solving the Ornstein-Zernike equation. The other approach is based on a molecular field theory, where the potential of mean torque experienced by a mesogen in the liquid crystal phase is parameterized according to its molecular surface. In this case, the calculation of elastic constants is combined with the Monte Carlo sampling of single molecule conformations. Using these different approaches, but the same description, at the level of molecular geometry and torsional potentials, we have investigated the elastic properties of the nematic phase of two typical mesogens, 4 '-n-pentyloxy-4-cyanobiphenyl and 4 '-n-heptyloxy-4-cyanobiphenyl. Both methods yield K-3(bend) > K-1 (splay) > K-2 (twist), although there are some discrepancies in the average elastic constants and in their anisotropy. These are interpreted in terms of the different approximations and the different ways of accounting for the structural properties of molecules in the two approaches. In general, the results point to the role of the molecular shape, which is modulated by the conformational freedom and cannot be fully accounted for by a single descriptor such as the aspect ratio. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4794920]en_US
dc.description.sponsorshipEge University BAPEge University [2011 Fen 044]; Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [BIDEB-2221]; Ateneo di Padova; Merck Ltden_US
dc.description.sponsorshipM.I.C. and A.N. are thankful to the Ege University BAP for the financial support (Project No. 2011 Fen 044). The Turkish group used the facilities of the ULAKBIM High Performance Computing Center. A.V.Z. acknowledges financial support from the Scientific and Technological Research Council of Turkey (TUBITAK) BIDEB-2221, which funded his stay at the Ege University. A.F. acknowledges financial support from the Ateneo di Padova through ex 60%. C.G. acknowledges Merck Ltd for a scholarship (Ph.D. School in Materials Science and Engineering of the Padova University).en_US
dc.identifier.doi10.1063/1.4794920en_US
dc.identifier.issn0021-9606
dc.identifier.issue11en_US
dc.identifier.pmid23534657en_US
dc.identifier.urihttps://doi.org/10.1063/1.4794920
dc.identifier.urihttps://hdl.handle.net/11454/47707
dc.identifier.volume138en_US
dc.identifier.wosWOS:000316544500039en_US
dc.identifier.wosqualityQ1en_US
dc.indekslendigikaynakWeb of Scienceen_US
dc.indekslendigikaynakPubMeden_US
dc.language.isoenen_US
dc.publisherAmer Inst Physicsen_US
dc.relation.ispartofJournal of Chemical Physicsen_US
dc.relation.publicationcategoryMakale - Uluslararası Hakemli Dergi - Kurum Öğretim Elemanıen_US
dc.rightsinfo:eu-repo/semantics/closedAccessen_US
dc.titleMolecular structure and elastic properties of thermotropic liquid crystals: Integrated molecular dynamics-Statistical mechanical theory vs molecular field approachen_US
dc.typeArticleen_US

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