Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, Mainz 55099, Germany.
J Chem Phys. 2010 Jul 7;133(1):014705. doi: 10.1063/1.3455504.
Monte Carlo simulations at constant pressure are performed to study coexistence and interfacial properties of the liquid-solid transition in hard spheres and in colloid-polymer mixtures. The latter system is described as a one-component Asakura-Oosawa (AO) model where the polymer's degrees of freedom are incorporated via an attractive part in the effective potential for the colloid-colloid interactions. For the considered AO model, the polymer reservoir packing fraction is eta(p) (r)=0.1 and the colloid-polymer size ratio is q[triple bond]sigma(p)/sigma=0.15 (with sigma(p) and sigma as the diameter of polymers and colloids, respectively). Inhomogeneous solid-liquid systems are prepared by placing the solid fcc phase in the middle of a rectangular simulation box, creating two interfaces with the adjoined bulk liquid. By analyzing the growth of the crystalline region at various pressures and for different system sizes, the coexistence pressure p(co) is obtained, yielding p(co)=11.576 k(B)T/sigma(3) for the hard-sphere system and p(co)=8.00 k(B)T/sigma(3) for the AO model (with k(B) as the Boltzmann constant and T as the temperature). Several order parameters are introduced to distinguish between solid and liquid phases and to describe the interfacial properties. From the capillary-wave broadening of the solid-liquid interface, the interfacial stiffness is obtained for the (100) crystalline plane, giving the values gamma approximately 0.49 k(B)T/sigma(2) for the hard-sphere system and gamma approximately 0.95 k(B)T/sigma(2) for the AO model.
在恒定压力下进行蒙特卡罗模拟，以研究硬球和胶体-聚合物混合物中液-固转变的共存和界面性质。后一种系统被描述为一个单组分的 Asakura-Oosawa (AO) 模型，其中聚合物的自由度通过胶体-胶体相互作用的有效势中的吸引部分来包含。对于所考虑的 AO 模型，聚合物储层堆积分数为 eta(p) (r)=0.1，胶体-聚合物大小比为 q[triple bond]sigma(p)/sigma=0.15（其中 sigma(p) 和 sigma 分别为聚合物和胶体的直径）。通过在矩形模拟盒的中间放置固相反方晶相，在相邻的体相液体中创建两个界面，制备不均匀的固-液系统。通过分析在不同压力和不同系统尺寸下晶体区域的生长，得到共存压力 p(co)，对于硬球系统，p(co)=11.576 k(B)T/sigma(3)，对于 AO 模型，p(co)=8.00 k(B)T/sigma(3)（其中 k(B) 是玻尔兹曼常数，T 是温度）。引入了几个序参数来区分固相与液相，并描述界面性质。从固-液界面的毛细波展宽中，得到了（100）晶面的界面硬度，对于硬球系统，得到了大约 0.49 k(B)T/sigma(2)的值，对于 AO 模型，得到了大约 0.95 k(B)T/sigma(2)的值。
