( 1. 湖南大学 应用物理系, 长沙 410082;
2. 湖南大学 材料科学与工程学院, 长沙 410082)
摘 要: 应用分子动力学， 结合分析型嵌入原子模型研究了Ag低指数面的声子频率、 声子线宽度、 原子振动振幅和层结构因子随温度的变化关系。 结果表明， 计算值与已有的实验数据比较相符； (110)面的原子振动振幅表现出明显的各向异性； 由声子频率随温度变化关系得到的非谐常数表明(111)面的非谐效应最弱。 计算出的反映表面长程有序特征的层结构因子表明， (111)面没有表面熔化， 而(100)、 (110)面分别在低于体熔点的100 K与250 K时出现了表面熔化。
关键字: 表面非谐效应； 分子动力学； 嵌入原子模型
（ 1. Department of Applied Physics, Hunan University, Changsha 410082, China;
2. College of Materials Science and Engineering, Hunan University,
Changsha 410082, China）
Abstract: The anharmonic effect of temperature on phonon frequency, line width, vibrational amplitude and structure factor of atoms for the low index surface of Ag were studied by molecular dynamics simulation and the analytic embedded atom method. The results show that the calculated values agree with the experimental data. The mean square amplitude of (110) plane surface exhibits anisotropic behavior. The calculated anharmonic constants indicate that the anharmonic effect of (111) plane is the smallest. The surface melting temperature is determined by calculating layer order structure factor. The (111) plane surface does not exhibit surface melting, but the (100) and (110) plane surfaces begin to melt at 100 K and 250 K below bulk melting temperature, respectively.
Key words: surface anharmonic effect; molecular dynamics; embeded atom method
