Step free energies at faceted solid-liquid interfaces from equilibrium molecular dynamics simulations.
Step free energies at faceted solid-liquid interfaces from equilibrium molecular dynamics simulations.
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DOI：
10.1063/1.4769381
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发表时间：
2012-11
期刊：
影响因子：
--
通讯作者：
T. Frolov;M. Asta
中科院分区：
文献类型：
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作者：
T. Frolov;M. Asta
在这项工作中，提出了一种基于原子模拟的方法来计算多面固液界面的台阶自由能。该方法被证明是在应用程序中的元素Si（111）界面，与经典的Stillinger-Weber势建模。该方法利用绝热捕获过程，并涉及模拟系统与共存的固体和液体相分离的多面界面含有不同大小的岛屿，计算相应的平衡温度。我们表明，计算的共存温度的界面的几何形状的强烈影响。我们发现，岛的半径是成反比的过热，使我们能够计算步骤自由能拟合模拟数据内的经典成核理论的形式主义。计算出台阶自由能γ（st）= 0.103 ± 0.005 × 10（-10）J/m。在这项工作中概述的方法铺平了道路，步骤的自由能的计算有关的多面晶体从液体混合物的固化，如在纳米线生长中遇到的气-液-固机制和合金铸造。目前的工作还表明，在低过冷度的Stillinger-Weber原子间势的硅倾向于结晶的纤锌矿，而不是金刚石立方结构。
In this work a method is proposed for computing step free energies for faceted solid-liquid interfaces based on atomistic simulations. The method is demonstrated in an application to (111) interfaces in elemental Si, modeled with the classical Stillinger-Weber potential. The approach makes use of an adiabatic trapping procedure, and involves simulations of systems with coexisting solid and liquid phases separated by faceted interfaces containing islands with different sizes, for which the corresponding equilibrium temperatures are computed. We demonstrate that the calculated coexistence temperature is strongly affected by the geometry of the interface. We find that island radius is inversely proportional to superheating, allowing us to compute the step free energy by fitting simulation data within the formalism of classical nucleation theory. The step free energy value is computed to be γ(st) = 0.103 ± 0.005 × 10(-10) J/m. The approach outlined in this work paves the way to the calculation of step free energies relevant to the solidification of faceted crystals from liquid mixtures, as encountered in nanowire growth by the vapor-liquid-solid mechanism and in alloy casting. The present work also shows that at low undercoolings the Stillinger-Weber interatomic potential for Si tends to crystallize in the wurtzite, rather than the diamond-cubic structure.