Gabriëlse Alexander, Löwen Hartmut, Smallenburg Frank
Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany.
Materials (Basel). 2017 Nov 7;10(11):1280. doi: 10.3390/ma10111280.
In many cases, the stability of complex structures in colloidal systems is enhanced by a competition between different length scales. Inspired by recent experiments on nanoparticles coated with polymers, we use Monte Carlo simulations to explore the types of crystal structures that can form in a simple hard-core square shoulder model that explicitly incorporates two favored distances between the particles. To this end, we combine Monte Carlo-based crystal structure finding algorithms with free energies obtained using a mean-field cell theory approach, and draw phase diagrams for two different values of the square shoulder width as a function of the density and temperature. Moreover, we map out the zero-temperature phase diagram for a broad range of shoulder widths. Our results show the stability of a rich variety of crystal phases, such as body-centered orthogonal (BCO) lattices not previously considered for the square shoulder model.
在许多情况下，胶体系统中复杂结构的稳定性通过不同长度尺度之间的竞争得以增强。受近期聚合物包覆纳米颗粒实验的启发，我们使用蒙特卡罗模拟来探索在一个简单的硬核方肩模型中能够形成的晶体结构类型，该模型明确纳入了粒子间两种偏好距离。为此，我们将基于蒙特卡罗的晶体结构发现算法与使用平均场胞理论方法获得的自由能相结合，并针对方肩宽度的两个不同值绘制出作为密度和温度函数的相图。此外，我们还绘制了广泛肩宽范围内的零温相图。我们的结果表明了多种晶体相的稳定性，比如此前未对方肩模型考虑过的体心正交（BCO）晶格。
