钨中空位及其团簇的能量学和动力学性质参数

Energetics and Dynamics Properties of Vacancies and Their Clusters in Tungsten

在总结前人钨中空位及其团簇的能量学和动力学行为的研究成果基础上,采用第一性原理方法系统计算了钨中空位及其团簇的结合能和扩散能垒。研究发现,交换关联泛函PW91和PBE较PBEsol、AM05和LDA更适合用于计算钨空位的能量学性质。基于第一性原理计算结果对文献中单空位形成能、双空位作用性质等争议性问题进行了讨论,并对钨经验势进行了评估。研究结果表明,钨中孤立单空位间总是相互排斥,而空位团簇(Vn>3)对单空位具有很强的吸引作用,其结合能随着所含空位个数增多呈现波动性增大的趋势。空位团簇稳定结构可通过最小化Wigner-Seitz表面积来确定,其结合能与Vn与Vn-1之间的Wigner-Seitz面积之差呈正比。

Based on the previous research results of the energetics and dynamics of vacancies and their clusters in tungsten,first-principles methods were used to systematically calculate binding energy and diffusion energy barriers of vacancies and their clusters.The results show that the electron exchange-correlation functionals PW91 and PBE are more suitable for calculating the energetic properties of vacancies in tungsten than PBEsol,AM05 and LDA functionals.Based on the first-principles calculation results,controversial issues such as the formation energy of the single vacancy and the nature of their interaction in the literature were discussed,and the empirical potential of tungsten was evaluated.The results show that the isolated single vacancies in tungsten always repel each other,while the vacancy clusters(Vn>3)have a strong attraction to single vacancy,and their binding energy increases with the number of vacancies in the cluster.The stable structure of vacancy clusters can be determined by minimizing their Wigner-Seitz surface area,and their binding energy is proportional to the difference in Wigner-Seitz area between Vn and Vn-1.