Bates M A
Department of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Phys Rev E Stat Nonlin Soft Matter Phys. 2001 Nov;64(5 Pt 1):051702. doi: 10.1103/PhysRevE.64.051702. Epub 2001 Oct 12.
The phase behavior of a mesogenic lattice-gas model consisting of freely rotating spins located at the sites of a three-dimensional cubic lattice has been studied using grand canonical Monte Carlo simulations. When two neighboring sites are occupied, the spin vectors interact via the extensively studied anisotropic Lebwohl-Lasher potential, plus an isotropic term of variable strength. The interaction between occupied and empty sites and two empty sites is taken to be zero. If the parameter governing the strength of the isotropic term is zero, the model exhibits an isotropic fluid-nematic transition, which becomes increasingly stronger as the temperature is lowered. The additional isotropic term is found to be important if the model is to reproduce experimental phase behavior, that is, to exhibit both nematic-vapor coexistence at low temperature and isotropic-vapor coexistence at higher temperatures.
利用巨正则蒙特卡罗模拟研究了一种介晶晶格气体模型的相行为，该模型由位于三维立方晶格位点上的自由旋转自旋组成。当两个相邻位点被占据时，自旋矢量通过广泛研究的各向异性勒布沃尔-拉舍势相互作用，再加上一个强度可变的各向同性项。被占据位点与空位点以及两个空位点之间的相互作用被视为零。如果控制各向同性项强度的参数为零，该模型会呈现各向同性流体向向列相的转变，且随着温度降低，这种转变会越来越强烈。如果该模型要重现实验相行为，即在低温下呈现向列相-气相共存以及在较高温度下呈现各向同性相-气相共存，那么额外的各向同性项被发现是很重要的。
