Ab initio study of planar faults in bcc Fe and Mo

The ratio of a generalized stacking-fault (GSF) energy and a free surface energy is an important parameter to describe the brittle versus ductile behavior of materials [1]. However, GSF energy values calculated with different empirical potentials are scattered over a wide range, depending on the selected poentials [2,3]. In this study, we calculated the GSF energies of Fe and Mo, by using quantum mechanical ab initio methods based on density functional theory (DFT). We crosschecked the results with those from the ultra soft pseudopotential (US-PP) and the projector augmented wave (PAW) potential , to investigate the effect of 3p electrons treated as core or valence electrons in transition metals. Further we investigated the effect of an atomic relaxation on the GSF energy.