硅团簇拉伸/压缩性能的分子动力学模拟

Molecular dynamics simulation of tension/compression properties of Si cluster

采用基于Stillinger-Weber(SW)势的分子动力学方法模拟了Si13团簇温度T分别为300K,50 K,5 K下的拉伸/压缩过程,得出了Si13团簇拉伸/压缩的力与应变的曲线图,讨论了不同温度下Si13拉伸/压缩的力学特性以及拉伸与压缩特性的差异。研究表明,拉伸/压缩初始阶段力与应变呈线性关系,拉伸时温度越高受力越大,压缩时正好相反,而且同等应变下拉伸时的力明显高于压缩时的力;当拉伸应变达到承载极限,继续拉伸,力突然变得很小,随后力与应变又呈现出与初始阶段相同的线性关系,这是团簇所特有的现象。

According to molecular dynamics,the process of tension and compression of Si13 cluster is calculated by using Stillinger-Weber（SW） potential at the temperatures of 300 K,50 K and 5 K.The force-strain relation curve of tension and compression of Si cluster is obtained.The mechanical properties of Si13 at different temperatures and the differences between tension and compression are analyzed.The result shows that the relation between force and strain is linear at the initial phase of tension and compression.The force is increased when temperature is higher in the tension.It is on the contrary in the compression.The tensile force is greater than the compressive force in the same strain.When the tensile strain reaches the limit load,if the cluster is still drawn,the force will suddenly become very small.Then the force and strain show the same linear relationship with the initial phase,which is a phenomenon unique to nano-rods and blocks.