Belgin Kocak

Pressure depended elastic, vibration and optical properties of NbIrSn from first principles calculations

Abstract We have reported first principles calculations based on the density functional theory within the local density approximation to explain the structural, electronic, elastic, vibration (phonon dispersion curves and one-phonon density of states) and optical properties for NbIrSn, which is semiconductor half Heusler compound with a cubic MgAgAs type structure. The obtained results are compared with the available other theoretical data. Our band structure calculations show that NbIrSn has indirect energy band gap of ∼1 eV at Γ-X Brillouin zone. The elastic properties, namely, bulk modulus, elastic constants, shear modulus, Young’s modulus, Poisson’s ratio, lame constants and Kleinmann parameter, are calculated under high pressure. The pressure effects for optical properties including the real and imaginary parts of the complex dielectric constant, refractive index n(ω), extinction coefficient k(ω), energy loss function L(ω) and reflectivity R(ω) are also computed and discussed.

Analysis of the structural, electronic and optic properties of Ni doped MgSiP2 semiconductor chalcopyrite compound

The structural, electronic band structure and optic properties of the Ni doped MgSiP2 chalcopyrite compound have been performed by using first-principles method in the density functional theory (DFT) as implemented in Vienna Ab-initio Simulation Package (VASP). The generalized gradient approximation (GGA) in the scheme of Perdew, Burke and Ernzerhof (PBE) is used for the exchange and correlation functional. The present lattice constant (a) follows generally the Vegard’s law. The electronic band structure, total and partial density of states (DOS and PDOS) are calculated. We present data for the frequency dependence of imaginary and real parts of dielectric functions of Ni doped MgSiP2. For further investigation of the optical properties the reflectivity, refractive index, extinction coefficient and electron energy loss function are also predicted. Our obtained results indicate that the lattice constants, electronic band structure and optical properties of this compound are dependent on the substitution co...

Structural, elastic, thermodynamic and lattice dynamic properties of PrX (X = Sb, Bi)

Abstract First principles calculations for rare earth compounds PrSb and PrBi in NaCl(B1), CsCl(B2), ZB(B3), WC(Bh) and CuAu(L1o) structures have been performed using density functional theory within the generalized gradient approximation. For the total-energy calculation, the projected augmented plane-wave implementation of the Vienna ab-initio simulation package has been used. Our structural results are consistent with the available experimental and other theoretical data. The phonon dispersion curves and corresponding one-phonon density of states (DOS) for both compounds are also computed in NaCl(B1) structure which is energetically more stable than the other structures. In addition to these properties, the temperature/pressure variation of the volume, thermal expansion coefficient, heat capacity are calculated in over wide pressure and temperature ranges.