Ab initio calculation of point defect energies and atom migration profiles in varying surroundings in L1_2-ordered intermetallic compounds

摘要

Formation energies of antisite defects and vacancies were derived for the L1_2-ordered intermetallics Ni_3Al, Ni_3Ga, Pt_3Ga, and Pt_3In by a supercell ab initio approach. A thermodynamic treatment of point-like defects was then used for the calculation of temperature-dependent defect properties. Energy profiles for atom jumps in Ni_3Al in systematically varied atomic neighborhoods were calculated by statically displacing the jumping atom or by using a nudged elastic band method. It is discussed how a kinetic Monte-Carlo model can be modified so that the jump barrier height reflects the strongest neighborhood influences.