The kinetics of homogeneous melting beyond the limit of superheating
The kinetics of homogeneous melting beyond the limit of superheating
复制标题
DOI：
10.1063/1.3605601
复制
发表时间：
2011-07-14
影响因子：
4.4
通讯作者：
Gillan, M. J.
中科院分区：
文献类型：
--
作者：
Alfe, D.;Cazorla, C.;Gillan, M. J.
采用分子动力学模拟方法研究了过热晶体均匀熔化的时间尺度。所使用的相互作用模型是一个嵌入原子模型的Fe在以前的工作中，和熔融过程中模拟的微正则（N，V，E）系综。我们研究了含有96 - 7776个原子的周期重复系统，初始系统总是没有自由表面或其他缺陷的完美晶体。对于每个选定的总能量E和原子数N，我们进行数百次统计独立的模拟，每次模拟持续500 ps至10 ns，以收集熔化发生前等待时间tau（w）的统计数据。我们发现τ（w）的概率分布大致呈指数分布，平均值强烈依赖于晶体初始稳定温度超过其他研究人员确定的过热极限的过量。平均值）也以我们已经量化的方式强烈依赖于系统大小。对于类似于100个原子的非常小的系统，我们观察到固态和液态之间的持续交替，我们解释了为什么会发生这种情况。我们的研究结果使我们能够得出结论，最近提出的Z方法的可靠性，用于确定模拟材料的熔化性能，并建议方法的错误的校正方法。(C)2011年美国物理学会。[doi：10.1063/1.3605601]
Molecular dynamics simulation is used to study the time-scales involved in the homogeneous melting of a superheated crystal. The interaction model used is an embedded-atom model for Fe developed in previous work, and the melting process is simulated in the microcanonical (N, V, E) ensemble. We study periodically repeated systems containing from 96 to 7776 atoms, and the initial system is always the perfect crystal without free surfaces or other defects. For each chosen total energy E and number of atoms N, we perform several hundred statistically independent simulations, with each simulation lasting for between 500 ps and 10 ns, in order to gather statistics for the waiting time tau(w) before melting occurs. We find that the probability distribution of tau(w) is roughly exponential, and that the mean value depends strongly on the excess of the initial steady temperature of the crystal above the superheating limit identified by other researchers. The mean ) also depends strongly on system size in a way that we have quantified. For very small systems of similar to 100 atoms, we observe a persistent alternation between the solid and liquid states, and we explain why this happens. Our results allow us to draw conclusions about the reliability of the recently proposed Z method for determining the melting properties of simulated materials and to suggest ways of correcting for the errors of the method. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3605601]