Cálculo das constantes elásticas de um cristal líquido nemático: interação quadrupolar

• Ano de defesa: 2004
• Autor(a) principal: Freire, Fernando Carlos Messias
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual de Maringá; Brasil; Programa de Pós-Graduação em Física; UEM; Maringá, PR; Centro de Tecnologia
• Palavras-chave em Português: Constantes elásticas; Cristal líquido nemático; Ciências Exatas e da Terra; Física
• Link de acesso: http://repositorio.uem.br:8080/jspui/handle/1/2656

The elastic constants of an Nematic Liquid Crystals (NLC) system are evaluated by assuming that the quadrupolar interaction is the only one responsible for the NLC phase. We consider a more realistic and general situation, by assuming an interaction volume of ellipsoidal shape and a screened intermolecular (quadrupolar) potential. The introduction of an anisotropic interaction volume permits a detailed investigation of the behavior of the elastic constants as a function of this anisotropy, represented by the eccentricity e of the ellipsoidal volume. The bulk elastic constants are negative for e = 0 (spherical approximation) and monotonically increasing function of e, as e → 1, remaining negative in the entire range of the values of the eccentricity. On the contrary, the surface-like constants K13 and K24 are positive at e = 0 and become negative for e > 0:9. Therefore, the pseudo-molecular model shows that the quadrupolar interaction energy alone cannot give rise to an NLC phase.