Density functional theory study of the electronic structure and vibrational properties of some compounds

We have investigated the structural, electronic and vibrational properties ofMSi2(M=Co, Ni and Fe) in the calcium fluorite structure by using a GeneralGradient Approximation (GGA) for CoSi2, a Local Density Approximation(LDA) for NiSi2 and FeSi2 of the density functional theory and ab-initio pseudopotentials. The calculated lattice constants and bulk modulus of these threecompounds are in good agreement with the available experimental and othertheoretical results. The calculated lattice constants and electronic bandstructures have been used in the application of a linear response approachbased on density functional perturbation theory for phonon studies. Thecalculated phonon spectra of CoSi2 are in good agreement with availableexperimental data. A detailed discussion of atomic displacement pattern ofCoSi2 and NiSi2 are provided corresponding to the some phonon modes at the Γ,X and LKey Words : CoSi2, NiSi2, FeSi2, Density-functional theory, Electronicstructure, Phonons