Bcc Fe晶界模型简化方法的第一性原理研究

First-principles study on simplified methods of bcc Fe GB structure

基于密度泛函理论,计算了bcc Fe中Σ5(310)晶界平面位置处He_nV(n≤2)团簇的性质,同时以此数据结果为判断标准,分析了两种简化晶界模型的优劣,这两种简化晶界模型分别是自由表面晶界模型和重构的双晶界模型.选取三种不同取向的He_2V团簇,分别从结构、能量、计算资源消耗等多种角度进行对比,分析了所建模型的合理性与可行性.结果表明,两种简化模型都能够显著提高计算效率,但是自由表面晶界模型与初始完整晶界模型的计算结果更加吻合.同种简化方法及思路亦可应用于诸如非对称晶界的更复杂的晶界结构.

Based on the density functional theory （DFT）, the properties of HenV cluster on the grain plane of bcc Fe ∑5 （310） grain boundary （GB） were calculated. Furthermore, the results are used to analyze advantages and disadvantages of two simplified grain boundary models. One of the two simplified GB structures is named after the free surface model and the other is the reconstructed pair GB model. Three different types of He2V clusters are constructed to measure the rationality and feasibility of the two simplified GB models from various aspects such as configurations, energy characteristics and the corresponding resource consumptions. The results indicate that both simplified structures can significantly improve the computational efficiency, but results from the free surface model is more consistent with the initial perfect grain boundary. The same simplification methods can also be applied to more complex structures such as asymmetric grain boundary, etc.