Oropesa William G C, Nascimento Eduardo S, Vieira André P
Universidade de São Paulo, Instituto de Fisica, Rua do Matao, 1371, 05508-090, São Paulo, SP, Brazil.
Department of Physics, PUC-Rio, Rua Marquês de São Vicente 225, 22453-900 Rio de Janeiro, Rio de Janeiro, Brazil.
Phys Rev E. 2022 Apr;105(4-1):044705. doi: 10.1103/PhysRevE.105.044705.
We employ a lattice-gas extension of the Maier-Saupe model with discrete orientation states to study the phase behavior of a statistical model for biaxial nematogenic units in mean-field theory. The phase behavior of the system is investigated in terms of the strength of isotropic interaction between anisotropic objects, as well as the degree of biaxiality and the concentration of those units. We obtain phase diagrams with isotropic phases and stable biaxial and uniaxial nematic structures, various phase coexistences, many types of critical and multicritical behaviors, such as ordinary vapor-liquid critical points, critical end points, and tricritical points, and distinct Landau-like multicritical points. Our results widen the possibilities of relating the phenomenological coefficients of the Landau-de Gennes expansion to microscopic parameters, allowing an improved interpretation of theoretical fittings to experimental data.
我们采用具有离散取向态的迈尔 - 绍佩模型的晶格气体扩展，在平均场理论中研究双轴致液晶单元统计模型的相行为。根据各向异性物体之间各向同性相互作用的强度、双轴性程度以及这些单元的浓度来研究系统的相行为。我们得到了具有各向同性相以及稳定的双轴和单轴向列相结构、各种相共存、多种类型的临界和多临界行为（如普通气 - 液临界点、临界端点和三临界点）以及独特的类朗道多临界点的相图。我们的结果拓宽了将朗道 - 德热纳展开的唯象系数与微观参数联系起来的可能性，从而能够更好地解释理论对实验数据的拟合。
