Energetics of intrinsic point defects in aluminium via orbital-free density functional theory

The formation and migration energies for various point defects, including vacancies and self-interstitials, in aluminium are systematically reinvestigated using the supercell approximation in the framework of orbital-free density functional theory. In particular, the finite-size effects and the accuracy of various kinetic energy density functionals are examined. It is demonstrated that as the supercell size N-s increases, the finite-size errors asymptotically decrease as O(1/N-s(3)). Notably, the formation energies of self-interstitials converge much more slowly than that of vacancies. With carefully chosen kinetic energy density functionals, the calculated results agree quite well with the available experimental data and those obtained through Kohn-Sham density functional theory, which has an exact kinetic term.