( 1. 湖南大學 應用物理系, 長沙 410082;
2. 湖南大學 材料科學與工程學院, 長沙 410082)
摘 要: 應用分子動力學， 結(jié)合分析型嵌入原子模型研究了Ag低指數(shù)面的聲子頻率、 聲子線寬度、 原子振動振幅和層結(jié)構(gòu)因子隨溫度的變化關(guān)系。 結(jié)果表明， 計算值與已有的實驗數(shù)據(jù)比較相符； (110)面的原子振動振幅表現(xiàn)出明顯的各向異性； 由聲子頻率隨溫度變化關(guān)系得到的非諧常數(shù)表明(111)面的非諧效應最弱。 計算出的反映表面長程有序特征的層結(jié)構(gòu)因子表明， (111)面沒有表面熔化， 而(100)、 (110)面分別在低于體熔點的100 K與250 K時出現(xiàn)了表面熔化。
關(guān)鍵字: 表面非諧效應； 分子動力學； 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
