Department of Physics, Indian Institute of Science, C. V. Raman Ave, Bengaluru 560012, India.
Soft Matter. 2019 Sep 18;15(36):7275-7285. doi: 10.1039/c9sm00962k.
We report scalar activity induced phase separation and crystallization in a system of 3-d Lennard-Jones particles taken at state points spanning from the gas to the liquid regime using molecular dynamics simulation (MD). Scalar activity was introduced by increasing the temperature of half of the particles (labeled 'hot') while keeping the temperature of the other half constant at a lower value (labeled 'cold'). The relative temperature difference between the two subsystems is considered as a measure of the activity. From our simulations we observe that the two species tend to phase separate at sufficiently high activity ratio. The extent of separation is quantified by the defined order parameter and the entropy production during this process is determined by employing the two-phase thermodynamic (2PT) model and the standard modified Benedict-Webb-Rubin (MBWR) equation of state for a LJ fluid. We observe that the extent of the phase separation and entropy production increases with the density of the system. From a cluster analysis, we obtain the mean number of clusters ncl, and the mean size of the largest cluster n0 in the system, complementing each other. Bond orientation order parameters reveal that the so formed largest cluster also develops solid-like order consisting of both FCC and HCP packing. The presence of such crystalline order is also supported by a common neighbor analysis.
我们报告了在跨越气体到液体区域的状态点的 3-D Lennard-Jones 粒子系统中，通过分子动力学模拟（MD）引入标量活性诱导的相分离和结晶。通过提高一半粒子（标记为“热”）的温度，同时将另一半粒子的温度保持在较低值（标记为“冷”），引入了标量活性。两个子系统之间的相对温差被认为是活性的度量。从我们的模拟中，我们观察到在足够高的活性比下，两种物质倾向于相分离。通过定义的序参量来量化分离的程度，并且通过采用两相热力学（2PT）模型和 LJ 流体的标准修正 Benedict-Webb-Rubin（MBWR）状态方程来确定在此过程中的熵产生。我们观察到相分离和熵产生的程度随系统密度的增加而增加。通过聚类分析，我们获得了系统中平均簇数 ncl 和最大簇 n0 的平均大小，它们相互补充。键取向序参量表明，形成的最大簇也发展出具有 FCC 和 HCP 堆积的固态有序。这种晶态有序的存在也得到了邻居共同分析的支持。
