International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Calculations have been performed to study the structural, electronic, elastic, mechanical, thermodynamical and phonon properties of LuS and LuTe with the generalized gradient approximation for exchange and correlation. The calculated lattice constants, bulk modulus, its pressure derivative and elastic constants are calculated. The calculated values of lattice constant are in good agreement with the experimental and theoretical results. The elastic constants have been derived from the slopes of the acouistic branches in the phonon dispersion-curves. The electronic band structure and, total and partial density of states of these compounds have been computed and analysed. The phonon dispersions curves of LuSe and LuTe for B2 phase are computed using density functional perturbation theory (DFPT) with generalized gradient (GGA) approximations. We also used the quasiharmonic approximation to calculate some thermodynamic properties such as constant-volume specific heat capacity of the B2 phase of LuS and LuTe compounds.

The structural, elastic, electronic and phonon properties of Cu₂MnZ (Z=Al, Si, Ge, Ga, Sn, Sb, In) are investigated by first-principles calculations based on density functional theory. In this approach the local-density approximation (LDA) and generalized gradient approximation (GGA) are used for the exchange-correlation (XC) potential. The calculated lattice constant, bulk modulus, and elastic constants are in agreement with the previous ab-initio calculations and available experimental results. Electronic properties are discussed from the calculations of band structure and density of states. The direct method is used to derive the phonon frequencies and density of states.

First-principle calculations of structural, electronic, magnetic and elastic properties Os₂YPb (Y=Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) are presented, using the pseudo-potential plane waves method within the local density approximation (LDA) and the gradient generalized approximation (GGA) for the exchange and correlation potential. Results are given for lattice constant, elastic constant and bulk modulus. Our results of the electronic band structure and density of states show that these compounds are conductors. We have also presented phonon spectrum for Os₂YPb (Y=Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn).

We present ab initio calculations of the structural, electronic structures, elastic, thermodynamic and vibrational properties of the Ir3Hf compound in the L1₂ structure. The calculated lattice constants, bulk modulus, and first-order pressure derivative of the bulk modulus are reported for the L1₂ structure and compared with the earlier values. The elastic constants (C₁₁, C₁₂ and C₄₄) in L1₂ phase for Ir₃Hf compound is calculated using the energy-strain method. The calculated elastic constants satisfy the mechanical stability criterion. Electronic band structures and partial and total densities of states have been derived for Ir₃Hf. The band structures show metallic character; the conductivity is mostly governed by Ir 5d states. The phonon-dispersion curves and phonon total density of states based on the linear-response method have been investigated for this compound. Temperature variations of specific heat capacity in the range of 0–1000 K are obtained using the quasi-harmonic model.