VACANCY FORMATION IN CoSi2 AND NiSi2 FROM AB INITIO CALCULATION

Abstract

The lattice structure and electronic properties of perfect and defective CoSi 2 and NiSi 2 have been calculated using an ab initio plane-wave ultrasoft pseudopotential method based on the generalized gradient approximations (GGA). Special attention is paid to the formation energies of the vacancies, which largely depend on the atomic chemical potentials of Si and metal atom: in Si -rich limit, the formation energies of Si and Co vacancies are 2.39 eV and 0.56 eV whilst those are 1.53 eV and 2.29 eV in Co -rich limit in CoSi 2, respectively. For NiSi 2, the formation energies of Si and Ni vacancies are 0.56 eV and 1.25 eV in Si -rich limit and those are 0.04 eV and 2.3 eV in Ni -rich limit.