Fe中刃型位错芯的模型建立及电子结构研究

Model Construction and Electronic Structure Investigation of Edge Dislocation Core in Fe

本文用密度泛函理论框架下的离散变分方法 (DVM)研究了bccFe[10 0 ](0 0 1)刃型位错体系的电子结构 ,给出了结合能、原子间相互作用能以及电荷转移信息。结果表明 :通过结合能的计算可确立用于电子结构研究的团簇平衡构型。此外 ,原子间相互作用能的计算以及差分电荷密度分析表明在位错芯的压缩区 ,沿滑移面的原子对之间的化学键较强 ,而垂直于滑移面的键较弱。反之在位错的膨胀区 ,沿滑移面的原子对之间的化学键较弱 ,而垂直于滑移面的键较强 。

The electronic structure of the bcc Fe (001)edge dislocation core is investigated using the first principles discrete variational method(DVM).Using the results of the binding energy,we can define the atomic structure of the cluster model for the study of electronic structure of the dislocation.Through the calculation of the inter-atomic energy and the analysis of the charge density difference,we find that bonding character is closely related to the inter-atomic distance:the shorter the inter-atomic distance is,the stronger the bond is;the longer the inter-atomic distance,the weaker the bond is,and vice versa.At the same time,we notice that at the compressed zone of the dislocation core,the distance between two atoms along the slip plane is shorter than that of the atoms perpendicular to the slip plane,while the bond is stronger.And the situation at the expansion area is just contrary to that at the compressed zone,which is related to the movement of dislocation when it is exposed to the external force.