分子动力学模拟Gd原子在Cu低密勒表面的扩散过程

Molecular Dynamics Simulation of Gd Adatom Diffusion on Cu Low Index Surfaces

为了分析Gd吸附原子在Cu(001)、Cu(110)和Cu(111)表面的扩散机制,本文用分子动力学对该扩散过程进行模拟。模拟结果表明在Cu(001)和Cu(111)表面,Gd原子通过跳跃机制扩散;在Cu(110)表面,在[1 1 0]方向Gd原子通过跳跃机制扩散,而且多步跳跃频率很高,而在[0 0 1]方向则通过交换机制扩散。通过对扩散频率的拟合,发现在各种扩散机制都符合Arrhenius公式,从而确定了在Cu(001)和Cu(111)表面扩散势垒分别为0.19 eV和0.013 eV,在Cu(110)表面,沿[1 1 0]方向跳跃扩散势垒和沿[0 0 1]方向交换扩散势垒分别为0.097 eV和0.33 eV。

The diffusion mechanisms of Gd adatoms on Cu low index surfaces are, studied by molecular dynamics. The simulation results show that on Cu（001 ） and Cu（ 111 ） surfaces, the Gd adatoms diffuse by hopping, and the frequency of long jumps is very high at high temperature.On Cu（ll0） surface,along [110] direction the Gd adatoms diffuse by hopping,and the frequency of long jumps is also high,while along [001] direction,the Gel adatoms diffuse by exchanging.The diffusion coefficient or frequency of hopping and exchanging can be described by Arrhenius equation.The diffusion barriers on Cu（001） and Cu（111） surfaces are calculated to be 0.19 eV and 0.013 eV,respectively.While on Cu（110） surface,the hopping diffusion barrier along[ 110] direction is 0.097 eV,and the exchanging diffusion barrier along [001] direction is 0. 33eV.