标题： 双轴向列相晶格模型的相图：蒙特卡罗模拟研究 显示英文标题

标题： Phase diagram of a biaxial nematogenic lattice model: A Monte Carlo simulation study

摘要： 具有$D_{2h}$对称性的双轴分子晶格系统的相图，以及通过 Straley 四极对势相互作用，在 Sonnet-Virga-Durand 参数化 [A. M. Sonnet, E. G. Virga, and G. E. Durand, Phys. Rev. E{\bf 67}, 061701 (2003)] 下，已通过蒙特卡罗模拟确定。我们的结果证实，向列生成模型在从单轴向双轴向列的转变中，产生单轴和双轴向列宏观相以及一个三重临界点，这与平均场理论的预测一致。通过分析从能量概率分布导出的类似自由能函数的行为，检测了相变的阶数。报告了支持相图中单轴-双轴转变线上存在三重临界点的明确数值证据。尽管相图的性质在定性上与平均场研究中得到的结果相同，但三重点的位置与理论预测有显著差异。 显示英文摘要

摘要： The phase diagram for a lattice system of biaxial molecules possessing $D_{2h}$ symmetry and interacting with Straley's quadrupolar pair potential in Sonnet-Virga-Durand parameterization [A. M. Sonnet, E. G. Virga, and G. E. Durand, Phys. Rev. E {\bf67}, 061701 (2003)] has been determined using Monte Carlo simulation. Our results confirm that the nematogenic model yields both the uniaxial and biaxial nematic macroscopic phases along with a tricritical point in the transition from uniaxial to biaxial nematics as predicted in mean field theory. By analyzing the behavior of a free-energy-like function, derived from the probability distributions of energy, the order of phase transitions is detected. A conclusive numerical evidence in support of the existence of a tricritical point on the uniaxial-biaxial transition line in the phase diagram is reported. Although the nature of the phase diagram is qualitatively identical as obtained in the mean-field study however the location of the triple point differs significantly from theoretical prediction.