金刚石中单空位的分子动力学模拟

Molecular Dynamics Simulation of the Single Vacancy in Diamond

用分子动力学方法模拟了金刚石中单空位的最近邻原子和次近邻原子的弛豫过程 ,计算所用的碳原子间相互作用势为 Tersoff多体经验势 .结果表明 ,单空位的最近邻原子是向外弛豫的 ,平均弛豫幅度约为 2× 1 0 -2 nm,与 ab- inito方法和团簇理论得到的结果一致 ;次近邻原子在空位产生的瞬间是向内弛豫的 ,然后向内、外弛豫振荡 ,其弛豫的平均效果是向外的 ,平均弛豫幅度约为7× 1 0 -4 nm.空位的产生对最近邻原子的弛豫方向影响较大 ;空位产生后 ,最近邻原子被约束在偏离〈1 1 1〉方向约 0 .1 4°弛豫 .最近邻原子和次近邻原子间的平均键长缩短了约 4× 1 0 -3 nm.

The relaxation process of the nearest and second nearest neighbor atoms around a vacancy in diamond was simulated by molecular dynamics. The atomic interaction was described by Tersoff's many body empirical potential. The results show that the nearest neighbor atoms of the vacancy is 2×10 -2 nm outward, which is in good agreement with the results obtained by ab inito and cluster theory. The second nearest neighbor atoms move inward at the moment that the vacancy is introduced. Later, they vibrate outward or inward, and the average magnitude of relaxation is outward by 7×10 -4 nm. In addition, the relaxation orientation of the nearest neighbor atoms has changed and deviates from 〈111〉 direction by 0.14° after the introduction of the vacancy. The average bond length between the nearest and second nearest neighbor atoms of the vacancy is 0.15 nm and shortened by 4×10 -3 nm.