Pàmies Josep C, Cacciuto Angelo, Frenkel Daan
Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA.
J Chem Phys. 2009 Jul 28;131(4):044514. doi: 10.1063/1.3186742.
We report the phase diagram of interpenetrating Hertzian spheres. The Hertz potential is purely repulsive, bounded at zero separation, and decreases monotonically as a power law with exponent 5/2, vanishing at the overlapping threshold. This simple functional describes the elastic interaction of weakly deformable bodies and, therefore, it is a reliable physical model of soft macromolecules, like star polymers and globular micelles. Using thermodynamic integration and extensive Monte Carlo simulations, we computed accurate free energies of the fluid phase and a large number of crystal structures. For this, we defined a general primitive unit cell that allows for the simulation of any lattice. We found multiple re-entrant melting and first-order transitions between crystals with cubic, trigonal, tetragonal, and hexagonal symmetries.
我们报告了互穿赫兹球体的相图。赫兹势纯粹是排斥性的，在零间距处有界，并随着幂律单调递减，指数为5/2，在重叠阈值处消失。这个简单的函数描述了弱可变形体的弹性相互作用，因此，它是软大分子（如星形聚合物和球状胶束）的可靠物理模型。使用热力学积分和广泛的蒙特卡罗模拟，我们计算了流体相和大量晶体结构的精确自由能。为此，我们定义了一个通用的原胞，它允许模拟任何晶格。我们发现了具有立方、三角、四方和六方对称性的晶体之间的多次再入熔化和一级相变。
