Dipartimento di Fisica, Università di Roma Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy.
J Phys Chem B. 2013 Aug 15;117(32):9540-7. doi: 10.1021/jp404053t. Epub 2013 Jul 31.
We numerically calculate the equilibrium phase diagram of one-patch particles with 30% patch coverage. It has been previously shown that in the fluid phase these particles organize into extremely long tubelike aggregates (G. Munaò et al. Soft Matter 2013, 9, 2652). Here, we demonstrate by means of free-energy calculations that such a disordered tube phase, despite forming spontaneously from the fluid phase below a density-dependent temperature, is always metastable against a lamellar crystal. We also show that a crystal of infinitely long packed tubes is thermodynamically stable, but only at high pressure. The full phase diagram of the model, beside the fluid phase, displays four different stable crystals. A gas-liquid critical point, and hence a liquid phase, is not detected.
我们对具有 30%覆盖面积的单斑块粒子进行了平衡相图的数值计算。先前已经表明，在流体相中，这些粒子会自发地组装成非常长的管状聚集体（G. Munaò 等人，Soft Matter 2013, 9, 2652）。在这里，我们通过自由能计算表明，尽管这种无序管状相在密度依赖性温度下自发地从流体相中形成，但它始终相对于层状晶体处于亚稳状态。我们还表明，无限长的管状晶体是热力学稳定的，但仅在高压下才如此。该模型的完整相图除了流体相之外，还显示了四种不同的稳定晶体。没有检测到气-液临界点和相应的液相。
