Electronic structures of the 〈1 0 0〉{0 1 0}, 〈1 0 0〉{0 1 1} and 1/2〈1 1 1〉{0 1 1} edge dislocations in bcc iron

Abstract

The discrete variational method within the framework of density functional theory is used to study the electronic structures of the 〈1 0 0〉{0 1 0}, 〈1 0 0〉{0 1 1} and 1/2〈1 1 1〉{0 1 1} edge dislocations in bcc Fe, and the density of states, the charge density, the structural energy and the interatomic energy are obtained. The results show that localized electronic states exist in the cores of the 〈1 0 0〉{0 1 0} and 〈1 0 0〉{0 1 1} edge dislocations, but not in the 1/2〈1 1 1〉{0 1 1} edge dislocation. The features of the 〈1 0 0〉{0 1 0} edge dislocation are similar to those of the 〈1 0 0〉{0 1 1} edge dislocation, but different from those of the 1/2〈1 1 1〉{0 1 1} edge dislocation. In addition, there is an intrinsic hindrance of the lattice to the dislocation motion, namely, an effect of trapping of lattice on the dislocation. For the 1/2〈1 1 1〉{0 1 1} edge dislocation, the interaction between the atoms along the slip direction is much stronger than that normal to the slip direction. However, in the 〈1 0 0〉 type edge dislocation, the interatomic bonds along and normal to the slip direction have almost the same strength, and the bond is even stronger normal to the slip direction in the 〈1 0 0〉{0 1 1} edge dislocation. The results show that the motion of the 1/2〈1 1 1〉 edge dislocation may be easier than that of the 〈1 0 0〉 edge dislocation under a stress field.