Effects of structural relaxation on the generalized stacking fault energies of hexagonal-close-packed system from first-principles calculations

In this paper, the effects of relaxation parameters on the first-principle-calculated generalized stacking fault energy (GSFE) were investigated. Two relaxing directions were considered, out-of-plane (N-direction) and in-plane (P-direction). N-direction is normal to the slip plane. P-direction is parallel to the slip plane and perpendicular to the slip direction. The results show that relaxation along the N-direction is essential, especially for the high-index slip plane; relaxation along the P-direction is needed when the atoms on the two sides of the slip direction are unsymmetrical. Discussions were made based on the first-principle calculated forces and the geometry of the atomic configurations of different slip systems.