The vacancy diffusion near diamond (001) surface by molecular dynamics simulation
空位在金刚石近(001)表面扩散的分子动力学模拟

The diffusion process of the vacancy near diamond(001) surface and the effects of temperature on the vacancy diffusion were investigated by molecular dynamics simulation. The results show that when the temperature is about 1000K, the vacancy in the second layer begins to diffuse to the surface. In the 1400_2000K temperature range, the vacancy can migrate to the surface. This result is in a good agreeement with that of experiment and other calculation. In the temperature range of 1400_1800K, two migration stages are observed in the vacancy diffusion process, which correspond to two maximums in the mean square displacement curves. In addition, the vacancy diffusion path was obtained without any constraints exposed on the atoms and the calculated diffusion barrier of the vacancy near diamond(001) surface is about 0^42 eV. We also discussed the effects of vacancy number and different vacancy arrangement on vacancy diffusion at a certain temperature.