Unified molecular field theory of nematic, smectic-A, and smectic-C phases

Grzegorz Pajak, Mikhail Osipov

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

A unified mean-field molecular theory of nematic (NU), smectic A (SmA), and smectic C (SmC) liquid crystal phases, composed of uniaxial nonpolar molecules, is developed taking into account the variation of all orientational and translational order parameters in these phases. Numerical results, obtained by direct global minimization of the free energy, are presented in the form of three typical phase diagrams of different topology. Temperature variation of the relevant order parameters in different sequences of phases is analyzed for various cross sections of the phase diagrams. The present model enables one to reproduce all possible sequences of phase transitions between the given phases including isotropic (Iso)-NU-SmA-SmC, Iso-NU-SmC, Iso-SmA-SmC, and Iso-SmC. The properties of the NAC point, where the NU, SmA, and SmC structures coexist, are considered in detail and the shape of the phase diagram in the vicinity of the NAC point is compared with existing experimental data.
LanguageEnglish
Article number012507
Number of pages12
JournalPhysical Review E
Volume88
DOIs
Publication statusPublished - 26 Jul 2013

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Field Theory
phase diagrams
Phase Diagram
Order Parameter
molecular theory
Global Minimization
topology
free energy
liquid crystals
Liquid Crystal
Mean Field
Free Energy
optimization
Cross section
Phase Transition
cross sections
Molecules
Experimental Data
Topology
Numerical Results

Keywords

  • unified
  • molecular field theory
  • nematic
  • smectic-A
  • smectic-C

Cite this

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abstract = "A unified mean-field molecular theory of nematic (NU), smectic A (SmA), and smectic C (SmC) liquid crystal phases, composed of uniaxial nonpolar molecules, is developed taking into account the variation of all orientational and translational order parameters in these phases. Numerical results, obtained by direct global minimization of the free energy, are presented in the form of three typical phase diagrams of different topology. Temperature variation of the relevant order parameters in different sequences of phases is analyzed for various cross sections of the phase diagrams. The present model enables one to reproduce all possible sequences of phase transitions between the given phases including isotropic (Iso)-NU-SmA-SmC, Iso-NU-SmC, Iso-SmA-SmC, and Iso-SmC. The properties of the NAC point, where the NU, SmA, and SmC structures coexist, are considered in detail and the shape of the phase diagram in the vicinity of the NAC point is compared with existing experimental data.",
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Unified molecular field theory of nematic, smectic-A, and smectic-C phases. / Pajak, Grzegorz; Osipov, Mikhail.

In: Physical Review E, Vol. 88, 012507, 26.07.2013.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Unified molecular field theory of nematic, smectic-A, and smectic-C phases

AU - Pajak, Grzegorz

AU - Osipov, Mikhail

PY - 2013/7/26

Y1 - 2013/7/26

N2 - A unified mean-field molecular theory of nematic (NU), smectic A (SmA), and smectic C (SmC) liquid crystal phases, composed of uniaxial nonpolar molecules, is developed taking into account the variation of all orientational and translational order parameters in these phases. Numerical results, obtained by direct global minimization of the free energy, are presented in the form of three typical phase diagrams of different topology. Temperature variation of the relevant order parameters in different sequences of phases is analyzed for various cross sections of the phase diagrams. The present model enables one to reproduce all possible sequences of phase transitions between the given phases including isotropic (Iso)-NU-SmA-SmC, Iso-NU-SmC, Iso-SmA-SmC, and Iso-SmC. The properties of the NAC point, where the NU, SmA, and SmC structures coexist, are considered in detail and the shape of the phase diagram in the vicinity of the NAC point is compared with existing experimental data.

AB - A unified mean-field molecular theory of nematic (NU), smectic A (SmA), and smectic C (SmC) liquid crystal phases, composed of uniaxial nonpolar molecules, is developed taking into account the variation of all orientational and translational order parameters in these phases. Numerical results, obtained by direct global minimization of the free energy, are presented in the form of three typical phase diagrams of different topology. Temperature variation of the relevant order parameters in different sequences of phases is analyzed for various cross sections of the phase diagrams. The present model enables one to reproduce all possible sequences of phase transitions between the given phases including isotropic (Iso)-NU-SmA-SmC, Iso-NU-SmC, Iso-SmA-SmC, and Iso-SmC. The properties of the NAC point, where the NU, SmA, and SmC structures coexist, are considered in detail and the shape of the phase diagram in the vicinity of the NAC point is compared with existing experimental data.

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