Polarizable potentials for metals: The density readjusting embedded atom method (DR-EAM)
Polarizable potentials for metals: The density readjusting embedded atom method (DR-EAM)
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DOI：
10.1103/physrevb.99.094106
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发表时间：
2019-03
影响因子：
3.7
通讯作者：
Hemanta Bhattarai;K. E. Newman;J. Gezelter
中科院分区：
文献类型：
--
作者：
Hemanta Bhattarai;K. E. Newman;J. Gezelter
在金属界面的模拟中，一些最广泛使用的经典分子动力学力场缺少金属行为的一个关键方面。我们提出了一种改进的嵌入原子方法（EAM），它允许通过处理每个原子周围的价密度作为一个波动的动力学量的金属的电子极化。密度由一组附加的涨落变量（及其共轭动量）表示，这些变量沿着核坐标传播。这种"密度调整EAM“（DR-EAM）几乎保留了传统EAM的所有有用特性，包括体弹性性能和表面能。然而，它也允许价电子密度响应于外部扰动而通过金属迁移。我们表明，DR-EAM可以成功地模拟极化响应外部电荷，捕捉图像电荷效应的原子模拟。DR-EAM还可以捕捉到金属在均匀电场中的一些行为，预测金属内部的表面充电和屏蔽。我们进一步表明，它预测合金中的组成原子之间的电荷转移，导致新的预测层状$\mathrm{L}{1}_{0}$结构的晶胞几何形状。
In simulations of metallic interfaces, a critical aspect of metallic behavior is missing from the some of the most widely used classical molecular dynamics force fields. We present a modification of the embedded atom method (EAM) which allows for electronic polarization of the metal by treating the valence density around each atom as a fluctuating dynamical quantity. The densities are represented by a set of additional fluctuating variables (and their conjugate momenta) which are propagated along with the nuclear coordinates. This ``density readjusting EAM'' (DR-EAM) preserves nearly all of the useful qualities of traditional EAM, including bulk elastic properties and surface energies. However, it also allows valence electron density to migrate through the metal in response to external perturbations. We show that DR-EAM can successfully model polarization in response to external charges, capturing the image charge effect in atomistic simulations. DR-EAM also captures some of the behavior of metals in the presence of uniform electric fields, predicting surface charging and shielding internal to the metal. We further show that it predicts charge transfer between the constituent atoms in alloys, leading to novel predictions about unit cell geometries in layered $\mathrm{L}{1}_{0}$ structures.