Noya Eva G, Bianchi Emanuela
Instituto de Química Física Rocasolano, CSIC, Calle Serrano 119, E-28006 Madrid, Spain.
J Phys Condens Matter. 2015 Jun 17;27(23):234103. doi: 10.1088/0953-8984/27/23/234103. Epub 2015 May 26.
The phase behaviour of inverse patchy colloid systems composed of spherical particles with two oppositely charged patches at the poles is investigated by simulation-based thermodynamic integration schemes. The interaction between the particles is derived via a coarse-grained model characterized by three system parameters: the charge imbalance between the bare colloid and the patches, the patch surface extension and the particle interaction range. Starting from a set of parameters for which a stacking of parallel layers is thermodynamically stable, the effect of each of these three parameters on the phase diagram is studied. Our results show that the region of stability of the layered solid phase can be expanded by increasing the charge imbalance and/or by reducing the interaction range. A larger patch size, on the other hand, stabilizes the layered structure with respect to the competing face centered cubic solid at high pressures but destabilizes it with respect to the fluid phase at low pressures. The location of the liquid-vapour critical point in the temperature versus density plane is also investigated: while the charge imbalance and the patch size affect mainly the critical density, a change of the interaction range has a substantial impact also on the critical temperature.
通过基于模拟的热力学积分方案，研究了由在两极带有两个相反电荷斑块的球形颗粒组成的反式斑胶体系统的相行为。颗粒之间的相互作用是通过一个粗粒化模型推导出来的，该模型由三个系统参数表征：裸胶体与斑块之间的电荷不平衡、斑块表面扩展以及颗粒相互作用范围。从一组参数出发，对于这些参数，平行层的堆叠在热力学上是稳定的，研究了这三个参数中的每一个对相图的影响。我们的结果表明，通过增加电荷不平衡和/或减小相互作用范围，可以扩大层状固相的稳定区域。另一方面，更大的斑块尺寸在高压下相对于竞争的面心立方固体使层状结构稳定，但在低压下相对于流体相使其不稳定。还研究了温度-密度平面中液-气临界点的位置：虽然电荷不平衡和斑块尺寸主要影响临界密度，但相互作用范围的变化对临界温度也有很大影响。
