Crystallography Reports

, Volume 45, Issue 3, pp 510–514 | Cite as

Nematic-isotropic phase transition in polar liquid crystals. 2. Role of dispersion interactions

  • A. V. Emel’yanenko
  • M. A. Osipov
Liquid Crystals


The present study furthers the development of the theory of the nematic-isotropic phase transition in the system of rodlike particles with large longitudinal dipoles. The effect of dispersion interactions between single molecules (monomers) and molecular pairs (dimers) on the transition temperature is considered. The crucial point of the approach used is existence of dimers in the system. Dispersion interactions are estimated within the framework of the model in which molecules consist of spherical blocks interacting according to the Lennard-Jones law. The direct pair-correlation functions are approximated by spherical invariants forming a complete system of functions. Then, these correlation functions are varied in order to study the behavior of the phase-transition temperature depending on the choice of the molecular model. It is shown that, depending on the molecule shapes, dimers can either destroy or stabilize the nematic order. It is also shown that the presence of dimers in the system decelerates an increase of the transition temperature (and, in many instances, can even reduce it) with an increase in the value of the molecular dipole.


Phase Transition Transition Temperature Liquid Crystal Single Molecule Dispersion Interaction 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    A. V. Emel’yanenko and M. A. Osipov, Kristallografiya 45(3), 549 (2000) [Crystallogr. Rep. 45 (3), 501 (2000)].Google Scholar
  2. 2.
    A. Perera and G. N. Patey, J. Chem. Phys. 89, 5861 (1988).ADSGoogle Scholar
  3. 3.
    A. G. Vanakaras and D. J. Photinos, Mol. Phys. 85, 1089 (1995).Google Scholar
  4. 4.
    C. Vega and S. Lago, J. Chem. Phys. 100, 6727 (1994).ADSGoogle Scholar
  5. 5.
    M. A. Osipov and A. Yu. Simonov, Khim. Fiz. 8(7), 992 (1989).Google Scholar
  6. 6.
    S. C. McGrother, A. Gil-Villegas, and G. Jackson, J. Phys. C: Solid State Phys. 8, 9649 (1996).Google Scholar
  7. 7.
    K. Satoh, Sh. Mita, and Sh. Kondo, Liq. Cryst. 20(6), 757 (1996).Google Scholar
  8. 8.
    K. Singer, A. Taylor, and J. V. L. Singer, Mol. Phys. 33, 1757 (1977).Google Scholar
  9. 9.
    S. Murad, D. J. Evans, and K. E. Gubbins, Mol. Phys. 37, 725 (1979).Google Scholar
  10. 10.
    D. J. Tildseley, W. B. Streett, and W. A. Steele, Mol. Phys. 39, 1169 (1980).Google Scholar
  11. 11.
    B. W. van der Meer and G. Vertogen, Molecular Physics of Liquid Crystals, Ed. by G. R. Luckhurst and G. W. Gray (Academic, New York, 1979).Google Scholar
  12. 12.
    L. Blum and A. J. Torruella, J. Chem. Phys. 56, 303 (1972).Google Scholar

Copyright information

© MAIK "Nauka/Interperiodica" 2000

Authors and Affiliations

  • A. V. Emel’yanenko
    • 1
  • M. A. Osipov
    • 2
  1. 1.Physics FacultyMoscow State UniversityVorob’evy gory, MoscowRussia
  2. 2.Shubnikov Institute of CrystallographyRussian Academy of SciencesRussia

Personalised recommendations