Different <i>Ab Initio</i> Approaches for Doping Descriptions: Tetragonal Deformation of Ni-Mn-Ga Alloys

Abstract

The influence of Co and Cu doping on Ni-Mn-Ga alloy is investigated using the different ab initio methods for description of chemical disorder. The exact muffin-tin orbital method in combination with the coherent-potential approximation provides almost identical profiles of total energies along the tetragonal deformation path compared to the supercell approach used within the projector-augmented wave method. On the other hand, the simple virtual crystal approximation exhibits different results and thus it is not able to describe doping in Ni-Mn-Ga alloy properly.

Effect of Magnetic Ordering on the Stability of Ni–Mn–Ga(–Co–Cu) Alloys Along the Tetragonal Deformation Path

“…This approximation does not take into account short-range interactions and atomic relaxations around the doping atoms, however, in full Heusler alloys, such short-range effects only have a negligible influence on the total energy landscape [43]. Contribution of these effects to the total energy is not bigger than 0.05 mRy/atom in case of Ni 2 MnGa as was shown in our previous study [44]. The exchange correlation was described using the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation [45], employing the scalar-relativistic and softcore approximations.…”