Rate of homogeneous crystal nucleation in molten NaCl.
Rate of homogeneous crystal nucleation in molten NaCl.
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DOI：
10.1063/1.1896348
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发表时间：
2005-05
期刊：
影响因子：
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通讯作者：
C. Valeriani;Eduardo Sanz;D. Frenkel
中科院分区：
文献类型：
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作者：
C. Valeriani;Eduardo Sanz;D. Frenkel
本文对中等过冷度下氯化钠熔体晶体成核速率进行了数值模拟。在这种情况下，成核速度太慢，无法用“蛮力”分子动力学模拟来研究。（“Tosi Fumi”）NaCl的熔化温度约为1060 K。我们研究了在T = 800和825 K时的晶体成核。我们观察到，在成核过程中形成的临界晶核具有散装NaCl的晶体结构。有趣的是，临界核明显是刻面的，核有立方体形状。我们已经计算了晶体成核率使用两种完全不同的方法，一种是基于估计的成核势垒的扩散穿越率，其他的基础上的前向通量采样和过渡界面采样方法。我们发现，这两种方法产生相同的结果在一个数量级。然而，当我们将外推的模拟数据与NaCl成核的唯一可用实验结果进行比较时，我们观察到近五个数量级的差异。我们讨论了这种差异的可能原因。
We report a numerical simulation of the rate of crystal nucleation of sodium chloride from its melt at moderate supercooling. In this regime nucleation is too slow to be studied with "brute force" molecular-dynamics simulations. The melting temperature of ("Tosi Fumi") NaCl is approximately 1060 K. We studied crystal nucleation at T = 800 and 825 K. We observe that the critical nucleus formed during the nucleation process has the crystal structure of bulk NaCl. Interestingly, the critical nucleus is clearly faceted, the nuclei have a cubical shape. We have computed the crystal-nucleation rate using two completely different approaches, one based on an estimate of the rate of diffusive crossing of the nucleation barrier, the other based on the forward flux sampling and transition interface sampling methods. We find that the two methods yield the same result within an order of magnitude. However, when we compare the extrapolated simulation data with the only available experimental results for NaCl nucleation, we observe a discrepancy of nearly five orders of magnitude. We discuss the possible causes for this discrepancy.