Cuetos A, Martínez-Haya B, Lago S, Rull L F
Departamento de Ciencias Ambientales, Universidad Pablo de Olavide, 41013 Seville, Spain.
J Phys Chem B. 2005 Jul 21;109(28):13729-36. doi: 10.1021/jp051834c.
A general approach based on the Parsons-Lee theory for soft repulsive molecular fluids is employed to investigate the nematogenic behavior of prolate thermotropic liquid crystals over a broad temperature range. The theory is solved for the particular case of the Kihara soft repulsive spherocylinder model, which is mapped into an effective hard core interaction with a temperature-dependent molecular diameter, expected to resemble the average size and shape of the soft molecules at a given temperature. The reduction of the effective molecular diameter with temperature in the Kihara soft repulsive fluid implies implicitly an increase of the elongation of the molecule and induces the stabilization of the nematic phase at smaller effective packing fractions, contrary to what is found for other fluid models. The rationalization of this effect in terms of excluded volume steric arguments is corroborated by the good general agreement between the Parsons-Lee approach and Monte Carlo simulations for the equation of state of the fluid in the vicinity of the isotropic-nematic transition.
基于帕森斯-李理论的软排斥分子流体通用方法被用于研究长棒状热致液晶在较宽温度范围内的向列行为。针对基哈拉软排斥球柱体模型的特殊情况求解该理论，该模型被映射为具有温度依赖分子直径的有效硬核相互作用，预期类似于给定温度下软分子的平均尺寸和形状。基哈拉软排斥流体中有效分子直径随温度降低隐含着分子伸长增加，并在较小的有效堆积分数下诱导向列相的稳定，这与其他流体模型的情况相反。帕森斯-李方法与蒙特卡罗模拟对于各向同性-向列转变附近流体状态方程的良好总体一致性证实了根据排除体积空间论点对这种效应的合理化解释。
