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Thermodynamic properties of noble metal clusters: molecular dynamics simulation |
| WU Zhi-min1, WU Zhi-min1, WANG Xin-qiang2, WANG Xin-qiang2, XIAO Xu-yang2, XIAO Xu-yang2, HE Huan-dian2, HE Huan-dian2, LUO Qiang2, LUO Qiang2 |
| 1.Department of Physics, College of Science, Chongqing University, Chongqing 400044, China; Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100080, China; 2.Department of Physics, College of Science, Chongqing University, Chongqing 400044, China; |
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Abstract The thermodynamics properties of noble metal clusters AuN, AgN, CuN, and PtN (N = 80, 106, 140, 180, 216, 256, 312, 360, 408, 500, 628, 736, and 864) are simulated by micro-canonical molecular dynamics simulation technique. The potential energy and heat capacities change with temperature are obtained. The results reveal that the phase transition temperature of big noble metal clusters (N "e312 for Au, 180 for Ag and Cu, and 360 for Pt) increases linearly with the atom number slowly and approaches gently to bulk crystals. This phenomenon indicates that clusters are intermediate between single atoms and molecules and bulk crystals. But for the small noble clusters, the phase transition temperature changes irregularly with the atom number due to surface effect. All noble metal clusters have negative heat capacity around the solid-liquid phase transition temperature, and hysteresis in the melting / freezing circle is derived in noble metal clusters.
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Issue Date: 05 September 2006
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