氧对体心立方铁中刃型位错上扭折电子结构的影响

Effect of Oxygen on Electronic Structure of Kink in the Edge Dislocation in Body-Centred Cubic Iron

利用离散变分方法和DMol方法,研究了氧对体心立方铁中[100](010)刃型位错上扭折电子结构的影响,计算了杂质偏聚能、原子格位能、电荷密度及态密度.计算结果表明:扭折对氧原子有捕获效应,氧进入体系后引起电荷重新分布,铁原子的4s4p轨道失去电子,氧原子2p轨道和铁原子3d得到电子,氧原子的2p轨道与近邻铁原子的3d4s4p轨道之间杂化,使得它们之间的成键有较强的方向性,有可能使材料韧性降低.

Using the first - principles self - consistent discrete variational method and DMol method based on density functional theory, we have investigated the effect of oxygen element on the electronic structure of the kink on the [ 100] （010） edge dislocations in body -centred cubic iron. Furthermore,we have calculated the impurity segregation energy, the structural energy, the density of states and the charge density. The results show that the system with oxygen atom is more stable than the clean kink system. Oxygen has low structural energy about -11.55 eV, which shows that oxygen stay at a site of energy valley. The result reflects the trapping effect of kink on oxygen. In addition, there is notable charge redistribution between oxygen and Fe atoms. Oxygen atom obtains electrons from its neighboring Fe atoms, and Fe atoms loss electrons when trace oxygen is introduced into interstitial sites in the kink. The results of charge density and density of states show that the strong orientation bonds are formed between oxygen and Fe atoms due to the hybridizations between 0 -p with Fe - 3d4s4p orbitals. This may be not beneficial to toughness of materials.