First-principles Calculation on Core Structures and Peierls Stress of a Screw Dislocation in BCC Iron

Predicting atomistic properties of a dislocation is a first step toward an understanding of plastic behavior of materials, in particular BCC metals. The core structure and Peierls stress of a screw dislocation in BCC iron have been determined using the first-principles calculations based on the density functional theory with the large-scale supercell containing 231 atoms. For the a0/2[111] screw dislocation of BCC iron, the core structure was found, using 1 × 1 × 4 k-point samplings, to be a symmetric displacement field with no broken symmetry, and the Peierls stress was determined to be 1.1GPa for the simple shear stress along (–110)<111>.