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In this work, we have examined the structural, phonon and anisotropic elastic properties of a hexagonal δ-WN compound via density functional theory. The obtained structural parameters and mechanical properties are in agreement with the other experimental and theoretical results. The present phonon dispersion curve and elastic constants indicate that the δ-WN compound is both mechanically and dynamically stable. The predicted elastic modulus shows that this compound possesses a high bulk modulus, shear modulus and Young’s modulus. The tabulated B/G and Poisson’s ratio have predicted that δ-WN has ductile behavior. According to the calculated minimum thermal conductivity, the hexagonal δ-WN compound can be used as thermal insulating material. Moreover, elastic anisotropy behavior has been analyzed with the different anisotropic indexes. The anisotropic elastic properties have been reported and discussed for the first time.

WOS: 000402518800006, A comprehensive investigation of the structural, elastic, and lattice dynamical properties for ZrMo2 and HfMo2 with C14, C15, C36, and CeCu2 phases are conducted using density functional total energy calculations. The results have showed that C15 phase for both materials is energetically more stable than C14, C36 and CeCu2 phases. We have also estimated the mechanical behaviours of these compounds, including mechanical stability, bulk modulus, Young's modulus, shear modulus, Poisson's ratio, ductility, and anisotropy. Additionally, the lattice dynamical properties are analyzed and discussed exhaustively for these phases. The calculated properties agree well with available experimental and theoretical data.

WOS: 000393723800015, First principles density functional theory (DFT) calculations have been used to investigate the structural, anisotropic elastic and electronic properties of ruthenium doped tungsten-diboride ternary compounds (W1-XRUxB2) for an increasing molar fraction of Ru atom from 0.1 to 0.9 by 0.1. Among the nine different compositions, W0.3Ru0.7B2 has been found as the most stable one due to the formation energy and band filling theory calculations. Moreover, the band structures and partial density of states (PDOS) have been computed for each x composition. After obtaining the elastic constants for all x compositions, the secondary results such as Bulk modulus, Young's modulus, Poisson's ratio, Shear modulus, and Vickers Hardness of polycrystalline aggregates have been derived and the relevant mechanical properties have been discussed. In addition, the elastic anisotropy has been visualized in detail by plotting the directional dependence of compressibility, Poisson ratio, Young's and Shear moduli. (C) 2016 Elsevier B.V. All rights reserved., Turkish Prime Ministry State Planning Agency [2011K120290], This work was supported by the Turkish Prime Ministry State Planning Agency under projects no. 2011K120290.

WOS: 000311503000024, By means of plane-wave density functional first-principles calculations within the generalized gradient approximation (GGA), we report the structural, elastic and mechanical properties of MB12 (M = Zr, Hf, Y, Lu) with UB12-type structure. The lattice constants, bulk modulus, elastic constants and related quantities such as Young's modulus, shear modulus, Zener anisotropy factor, Poisson's ratio and Cauchy pressure are calculated and compared with the available experimental and other theoretical data. A deeper understanding, the pressure variations of the lattice constants, bulk modulus, elastic constants and other mechanical properties are also analyzed in a wide pressure range (0-50 GPa) and their trends are discussed. Additionally, Mulliken population analysis is used to clarify the bonding nature of all compounds. Combining the bonding nature and the structural information, microhardnesses of all compounds are calculated theoretically and then the detailed comparisons between hardness and other mechanical properties such as bulk modulus and shear modulus are made. (C) 2012 Elsevier B.V. All rights reserved., Turkish Prime Ministry State Planning Agency [2011K120290], This work was supported by the Turkish Prime Ministry State Planning Agency under Projects No. 2011K120290.

WOS: 000301032100016, Based on density functional theory, we have studied the structural stability, elastic, mechanical, and lattice dynamical properties of BeB2, NaB2, and CaB2 compounds in AlB2, OsB2, and ReB2 structures, respectively. Generalized gradient approximation has been used for modeling exchange-correlation effects. Our calculations indicate that ReB2, AlB2, and OsB2 structures are energetically the most stable for BeB2, NaB2, and CaB2 compounds, respectively. The results show that these structures are both mechanically and dynamically stable. The bulk modulus, elastic constants, shear modulus, Young's modulus, Poisson's ratio, Debye temperature, sound velocities, and anisotropic factors are also calculated and discussed. Furthermore, the phonon dispersion curves and corresponding phonon density of states are presented. Our structural and some other results are in agreement with the available experimental and theoretical data. (C) 2011 Elsevier Ltd. All rights reserved.

WOS: 000300596000006, The structural, phase transition, elastic, lattice dynamic and thermodynamic properties of rare-earth compounds PrP and PrAs with NaCl (B1), CsCl (B2), ZB (B3), WC (B-h) and CuAu (L1(0)) structures are investigated using the first principles calculations within the generalized gradient approximation (GGA). For the total-energy calculation, we have used the projected augmented plane-wave (PAW) implementation of the Vienna Ab-initio Simulation Package (VASP). Specifically, some basic physical parameters, e.g. lattice constants, bulk modulus, elastic constants, shear modulus, Young's modulus and Poison's ratio, are predicted. The obtained equilibrium structure parameters are in excellent agreement with the experimental and theoretical data. The temperature and pressure variations of the volume, bulk modulus, thermal expansion coefficient, heat capacity and Debye temperature are calculated in wide pressure and temperature ranges. The phonon dispersion curves and corresponding one-phonon density of states (DOS) for both compounds are also computed in the NaCl (B1) structure. (C) 2011 Elsevier B.V. All rights reserved., Gazi University Research-Project Unit [05/2010-51], This work is supported by Gazi University Research-Project Unit under Project no: 05/2010-51.

WOS: 000296214300010, In this work, density functional theory calculations on the structural, mechanical, and lattice dynamical properties of AgB2 and AuB2 compounds in AlB2, OsB2, and ReB2 structures are reported. Generalized gradient approximation has been used for modeling exchange-correlation effects. The detailed information is given for the energetically most stable structure for AgB2 and AuB2 compounds. Specifically, the lattice parameters, bulk modulus, cohesive energies, elastic constants, shear modulus, Young's modulus, Poison's ratio, Debye temperature, sound velocities, and anisotropic factors are studied. The elastic properties are also studied under pressure. The phonon dispersion curves and corresponding phonon density of states are calculated and discussed. Our structural and some other results are in agreement with the available experimental and theoretical data. (C) 2011 Elsevier B.V. All rights reserved.

WOS: 000292725700001, The structural, mechanical, electronic and optical properties of orthorhombic PtSi and PtGe were investigated using norm-conserving pseudopotentials within the local density approximation in the frame of density functional theory. The calculated lattice parameters and bulk modulus for PtSi and PtGe have been compared with the experimental and theoretical values. The second-order elastic constants were calculated, and the other related quantities such as the Young's modulus, shear modulus, Poisson's ratio, anisotropy factor, sound velocities and Debye temperature have also been estimated. The linear photon-energy dependent dielectric functions and some optical properties such as the energy-loss function, the effective number of valance electrons and the effective optical dielectric constant were calculated. Our structural estimation and some other results are in agreement with the available experimental and theoretical data.

WOS: 000282453500010, First principles calculations are performed to investigate the structural, electronic, elastic, and thermodynamic properties of the less known PrN compound for various space groups: NaCl(Fm3m(2 2 5)), C5Cl(Pm3m (2 2 1)), ZB(F43m(2 1 6)), Wc(P6m2(1 8 7)), and CuAu (P4/mmm (1 2 3)). Our calculation indicates that the NaCl type structure is energetically more stable than the other phases. The calculated lattice parameters are consisted with available theoretical and experimental results. Our band structure calculations show that PrN possessess a semi-metallic character for both with and without spin polarized (SP) cases. The calculated elastic constants satisfy the mechanical stability conditions at all considered pressures and the present values are significantly higher than those of the previous results. The related mechanical properties such as Zener anisotropy factor (A), Poisson's ratio (v), Young's modulus (E), and shear modulus (C) are also computed for NaCl structure. The temperature/pressure-dependent behaviours of bulk modulus, Debye temperature, heat capacity, thermal expansion coeffient, and V/V-0 ratio estimated within the quasi-harmonic Debye model., Gazi University [05/2009-16], This work was supported by the Gazi University Research-Project Unit under Project no. 05/2009-16.

WOS: 000286112900018, The structural, elastic, electronic and optical properties of Zn1-xMgxSe ternary mixed crystals are investigated by utilizing the first-principles plane-wave pseudopotential method within the LDA approximations. Some basic physical properties, such as lattice constant, bulk modulus, second-order elastic constants (C-ij), Shear modulus, Young's modulus, Poison's ratio, Lame constants and the electronic band structures, are calculated. We have, also, predicted the optical properties such as dielectric functions, refractive index and energy loss function of these ternary mixed crystals. Our results agree well with the available data in the literature., Gazi University [05/2008-42], This work is supported by Gazi University Research-Project Unit under Project No: 05/2008-42.

We have investigated the structural, electronic, and optical properties of Zn1−xCaxSe ternary alloys using first principles calculations within the plane-wave pseudopotential method. Some basic physical properties, such as lattice constant, bulk modulus, electronic band structures, and optical properties (dielectric functions, refractive index, and energy loss function) were calculated. In addition, the effects of composition x on bulk modulus, band gap, refractive index and dielectric function were calculated. Our results agree well with the available data in the literature.

The structural, electronic and optical properties of CdxZn1-xS alloys have been studied using the first-principles plane-wave pseudopotential (PP) method within the local-density approximations (LDAs). The effects of composition on lattice constants, bulk modulus, band gap, dielectric functions, refractive index, extinction coefficient and energy loss function are investigated. It has been found that the lattice constants and bulk modulus change as almost linear for these alloys. Calculated electronic structure and density of states (DOS) of CdxZn1-xS alloys are discussed in terms of the contribution of Zn d, Cd d and p and S s and p states. Our results agree well with the available data in the literature. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

WOS: 000274222000019, A detailed theoretical study of structural, electronic, elastic, phonon, and thermodynamical properties of SmX (X = P, Sb, Bi) compounds is presented by performing ab-initio calculations based on density-functional theory using the Vienna ab-initio simulation package (VASP). For describing the interaction between electrons and ions, the projector-augmented wave (PAW) method is used. The generalized-gradient approximation (GGA) is chosen for the exchange-correlation functional. The calculated structural parameters, such as the lattice constant with and without spin-polarization (SP), bulk modulus, cohesive energy, second-order elastic constants, the electronic band structures and the related total density of states with and without SP and spin-orbit coupling (SOC) are presented. The high-pressure phase of all compounds is investigated and phase transition pressure from NaCl (B1) to high-pressure phase is determined. For B1 structure, the calculated values of lattice constants are compared with the available experimental and other theoretical data and bulk modulus values are compared with available other theoretical results. In order to gain further information, we have calculated Zener anisotropy factor (A), Poisson's ratio (nu), Young's modulus (E), shear modulus (C), elastic wave velocities, Debye temperature, phonon frequencies and one-phonon density of states for B1 structure of these three compounds. The temperature dependent behavior of heat capacity and entropy for these compounds in B1 phase is also presented. (C) 2009 Elsevier B.V. All rights reserved., Gazi University [05/2008-16], This work is supported by Gazi University Research-Project Unit under Project No: 05/2008-16.

Deligöz, Engin ( Aksaray, Yazar ), We have studied structural, thermodynamic, elastic, and electronic properties of cubic IrO2 polymorph via ab initio calculations within the LDA and GGA approximations. Basic physical properties, such as lattice constant, bulk modulus, second-order elastic constants (Cij), and the electronic band structures are calculated, and compared with available experimental values. We have, also, predicted the Young's modulus, Poison's ratio (ν), Anisotropy factor (A), sound velocities, and Debye temperature.

We have studied the structural, thermodynamics, elastic, and electronic properties of boron bismuth (BBi) compound in zinc-blende and rock-salt structures by performing ab initio calculations within the local density approximation. For the first time, we have calculated Debye temperature, melting temperature, phase transition pressure, phonon dispersion curves, density of state, and pressure dependences of the second-order elastic constants (C-ij) for this hypothetical compound. Calculations on the other basic key properties, such as the lattice constant, bulk modulus, and some band structural parameters are also repeated and compared with the other recent theoretical works. (C) 2006 Elsevier B.V. All rights reserved.

We present the results of our calculations on Boron antimony (BSb) compound in zinc-blende (ZB) and rock-salt (RS) structures by performing ab initio calculations within the local density approximation (LDA). Some basic physical properties, such as lattice constant, bulk modulus, cohesive energy, phase transition pressure, second-order elastic constants (C-ij), phonon frequencies, and some band structural parameters are calculated and compared with those obtained with other recent theoretical works. In order to further understand the behaviour of BSb compound, we have also predicted, the pressure-dependent behaviours of the band gap, second-order elastic constants (C-ij), Young's modulus, poison ratios (v), Anizotropy factor (A), sound velocities, and Debye temperature for this hypothetical compound. (C) 2007 Elsevier Ltd. All rights reserved.

WOS: 000364132300004, Using the generalized-gradient approximation (GGA) based on density functional theory, we have reported the structural, mechanical, electronic, and lattice dynamical properties of the intermetallic compounds Pd3X (X = Ti, Zr, Hf) with D0(24) and the L1(2) structures. The elastic constants were predicted using the stress-finite strain technique. We performed numerical estimations of the bulk modulus, shear modulus, Young's modulus, Poisson's ratio anisotropy factor, G/B ratio, and hardness. Our studies have showed that all Pd3X (X = Ti, Zr, Hf) with D0(24) and the L1(2) structures are mechanically stable and relatively hard materials with low compressibility, and they could be considered as ductile systems. Also, the phonon dispersion curves and total and partial density of states were calculated and discussed for Pd3X (X = Ti, Zr, Hf). We finally estimated some thermodynamic properties such as entropy, free energy, and heat capacity at the temperature range 0-1000 K. The calculated phonon frequencies of Pd3X (X = Ti, Zr, Hf) are positive, indicating the dynamical stability of the studied compounds. For the first time, we have performed the numerical estimation of lattice dynamical properties for the compounds and still awaits experimental confirmation. The obtained ground state properties are in good agreement with those of experimental and theoretical studies.

WOS: 000349310200030, First-principles calculations are used to investigate the structural, elastic and vibration properties of the binary intermetallic compounds AgRE (RE = Ho, Er, Tm) with a B2 (CsCl) structure using density functional theory. The calculated structural parameters, the bulk modulus and its derivative with respect to pressure are in good agreement with experimental and numerical data. Additionally, the negative energy of formation of AgRE (RE = Ho, Er, Tm) with a B2 structure is examined. The independent second order elastic constants and their related properties, which are essential for mechanical stability, are investigated under pressure (0-60 GPa). The phonon spectra and phonon density of states are also discussed. All calculated phonon modes for AgRE (RE = Ho, Er) are positive in the phonon dispersion diagrams., Gazi University Research-Project Unit [05/2010-51]; Ankara University Research-Project Unit [12B4343020], This work was supported by Gazi University Research-Project Unit under Project No. 05/2010-51 and by Ankara University Research-Project Unit under Project No. 12B4343020. The numerical calculations reported in this paper were performed at TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure).

WOS: 000349449900015, The anisotropic elastic properties of XYSb (X = Ti, Zr, Hf; Y = Si, Ge) compounds have been investigated by using first-principles calculations based on density functional theory. The calculated lattice parameters are in excellent agreement with the available experimental data. The computed elastic constants indicate that all compounds are mechanically stable according to the elastic stability criteria under pressure. We have calculated the bulk modulus, shear modulus, Young's modulus, Poisson's ratio, Debye temperature, and anisotropy value from the obtained elastic constants according to the Voigt-Reuss-Hill approximation. Additionally, the ductility and brittleness are characterized with the estimation from Pugh's rule (B/G) and Poisson's ratio. Furthermore, the elastic anisotropy have been visualized in detail by plotting the directional dependence of compressibility, Young's and shear moduli. (C) 2015 Elsevier Masson SAS. All rights reserved., Aksaray University Research [2013-58], This work is supported by Aksaray University Research- Project unit under Project No: 2013-58. The numerical calculations reported here were partially performed at Aksaray University, Science and Technology Application and Research Center.

WOS: 000336737500015, First principles calculations are performed to investigate the structural stability, elastic, lattice dynamical and thermal properties of osmium carbides with various crystal structures. Our calculation indicates that the I4Te type structure is energetically the most favourable for Os4C. Based on stress-strain relationships, elastic constants are obtained, and the relevant mechanical properties are also discussed. The phonon dispersion relation and the dynamical stability are also predicted. We have found that the predicted structures are mechanically stable as well as dynamically stable except for cubic-Os4C. Through the quasi-harmonic Debye model, the temperature and pressure effects on the bulk modulus, thermal expansion coefficient, heat capacity, Gruneisen parameter and Debye temperature are presented.

WOS: 000334990400001, By means of first principles calculations, we have studied the structural, elastic, and phonon properties of the Al12X (X = Mo, Tc, Ru, W, Re, and Os) compounds in cubic structure. The elastic constants of these compounds are calculated, then bulk modulus, shear modulus, Young's modulus, Possion's ratio, Debye temperature, hardness, and anisotropy value of polycrystalline aggregates are derived and relevant mechanical properties are compared with the available theoretical ones. Furthermore, the phonon dispersion curves, mode Gruneisen parameters, and thermo-dynamical properties such as free energy, entropy and heat capacity are computed and the obtained results are discussed in detail. (C) 2014 Elsevier Ltd. All rights reserved.

WOS: 000334934900041, PubMed: 24633776, The structural, mechanical, electronic, and optical properties of orthorhombic Bi2S3 and Bi2Se3 compounds have been investigated by means of first principles calculations. The calculated lattice parameters and internal coordinates are in very good agreement with the experimental findings. The elastic constants are obtained, then the secondary results such as bulk modulus, shear modulus, Young's modulus, Poisson's ratio, anisotropy factor, and Debye temperature of polycrystalline aggregates are derived, and the relevant mechanical properties are also discussed. Furthermore, the band structures and optical properties such as real and imaginary parts of dielectric functions, energy-loss function, the effective number of valance electrons, and the effective optical dielectric constant have been computed. We also calculated some non-linearities for Bi2S3 and Bi2Se3 (tensors of elasto-optical coefficients) under pressure.

WOS: 000330643000005, Structural, electronic, elastic and thermodynamic properties of Rh3X ( X = Zr, Nb, Ta) intermetallic compounds are investigated in the framework of density functional theory (DFT). The exchange-correlation (XC) potential is treated with the generalized gradient approximation (GGA) and local density approximation (LDA). The computed ground state properties agree well with the available theoretical and experimental values. The elastic constants are obtained by calculating the total energy versus volume conserving strains using Mehl model. The electronic and bonding properties are discussed from the calculations of band structures (BSs), densities of states and electron charge densities. The volume and bulk modulus at high pressure and temperature are investigated. Additionally, thermodynamic properties such as the heat capacity, thermal expansion and Debye temperature at high pressures and temperatures are also analyzed., Deanship of Scientific Research at King Saud University [RPG-VPP-088], The authors R. K., A. B., Z. A. A. and S. B. O acknowledge the financial support by the Deanship of Scientific Research at King Saud University for funding the work through the research group project No. RPG-VPP-088. The author A. Sayede thanks the Centre de Ressources Informatiques (CRI) of the University of Lille for providing the computational facilities.

WOS: 000326136200001, A detailed theoretical study of the structural, elastic and electronic properties of W1-xTcxB2 (x=0.1 similar to 0.9) alloys is carried out by using the plane-wave pseudopotential approach to the density-functional theory within the generalized gradient approximation (GGA). The most stable structure is found as W0.9Tc0.1B2 due to the lowest formation energy value and Band filling theory. Furthermore, the band structural and density of states (DOS) are computed for each composition x (0.1 similar to 0.9). The elastic constants of W1-xTcxB2 for all x composition are obtained, then the secondary results such as bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and hardness of polycrystalline aggregates are derived, and the relevant mechanical properties are also discussed. Moreover, we have predicted that W0.9Tc0.1B2 alloy is potential superhard material. (C) 2013 Elsevier Ltd. All rights reserved., Turkish Prime Ministry State Planning Agency [2011K120290], This work was supported by the Turkish Prime Ministry State Planning Agency under Projects no. 2011K120290.

WOS: 000320231600006, 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 similar to 1 eV at Gamma-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(omega), extinction coefficient k(omega), energy loss function L(omega) and reflectivity R(omega) are also computed and discussed.

WOS: 000319309300013, The electronic, mechanical, and vibrational properties of MgB7 are investigated by means of density functional theory as implemented in pseudo-potential plane wave approach. Using the calculated elastic constants, the bulk modulus, shear modulus, Young's modulus, Possion's ratio, Debye temperature, hardness, and anisotropy value were derived. It is found that MgB7 in considered structure is mechanically stable and exhibits brittle character according to the B/G criterion. The band structure of this compound is a semiconductor with an indirect band gap. Furthermore, the phonon dispersion, density of states, Born effective charge tensors, Gruneisen parameter, temperature-dependent variations of the internal energy, free energy, entropy, and heat capacity are also computed and discussed. (C) 2013 Elsevier Ltd. All rights reserved.

WOS: 000317123600059, Structural and mechanical properties of several rare-earth diborides were systematically investigated by first principles calculations. Specifically, we studied XB2, where X = Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Lu in the hexagonal AlB2, ReB2, and orthorhombic OsB2-type structures. The lattice parameters, bulk modulus, bond distances, second order elastic constants, and related polycrystalline elastic moduli (e. g., shear modulus, Young's modulus, Poisson's ratio, Debye temperature, sound velocities) were calculated. Our results indicate that these compounds are mechanically stable in the considered structures, and according to "Chen's method", the predicted Vickers hardness shows that they are hard materials in AlB2- and OsB2-type structures.

WOS: 000318179600006, The thermodynamic properties of AgB2 and AuB2 compounds in AlB2 and OsB2-type structures are investigated from first-principles calculations based on density functional theory (DFT) using projector augmented waves (PAW) potentials within the generalized gradient approximation (GGA) for modeling exchange-correlation effects, respectively. Specifically, using the quasi-harmonic Debye model, the effects of pressure and temperature, up to 100 GPa and 1400 K, on the bulk modulus, Debye temperature, thermal expansion, heat capacity and the Gruneisen parameter are calculated successfully and trends are discussed.

WOS: 000326197100007, The structural, mechanical and thermal properties of CeB2, PrB2, NdB2, and PmB2 compounds in hexagonal AlB2-type (P6/mmm) and ReB2-type structures (P6(3)/mmc) are investigated using density functional theory. The results indicate that those compounds with hexagonal AlB2 structure are the most stable among the considered structures. The mechanical properties are calculated according to the elastic constants by means of the Voigt-Reuss-Hill averaging scheme. The temperature dependence of various quantities such bulk modulus, Debye temperature, thermal expansion, heat capacity, and Gruneisen parameter have been analyzed using the quasi-harmonic Debye model.

WOS: 000316534400027, We have investigated the structural, elastic, electronic, vibration and thermodynamic properties of GdMg alloy using the methods of density functional theory within the generalized gradient approximation (GGA) for the exchange-correlation functional. We have presented the results on the basic physical parameters, such as the lattice constant, bulk modulus, pressure derivative of bulk modulus with and without spin-polarization (SP), second-order elastic constants, Zener anisotropy factor, Poisson's ratio, Young's modulus, and isotropic shear modulus. The thermodynamic properties of the considered compound are obtained through the quasi-harmonic Debye model. In order to obtain further information, we have also studied the pressure and temperature-dependent behavior of the volume, bulk modulus, thermal expansion coefficient, heat capacity, and Debye temperature in a wide temperature range of 0-1200 K. We have also calculated phonon frequencies and one-phonon density of states for B2 structure of GdMg compound. The temperature-dependent behavior of heat capacity and entropy obtained from phonon density of states for GdMg compound in B2 phase is also presented., Gazi University Research-Project Unit [05/2010-51], This work was supported by Gazi University Research-Project Unit under Project no. 05/2010-51.

WOS: 000297743800024, The structural, elastic and thermodynamic characteristics of CeGa2 compound in the AlB2 (space group: P6/mmm) and the omega trigonal (space group: P-3m1) type structures are investigated using the methods of density functional theory within the generalized gradient approximation (GGA). The thermodynamic properties of the considered structures are obtained through the quasi-harmonic Debye model. The results on the basic physical parameters, such as the lattice constant, the bulk modulus, the pressure derivative of bulk modulus, the phase-transition pressure (P (t) ) from P6/mmm to P-3m1 structure, the second-order elastic constants, Zener anisotropy factor, Poisson's ratio, Young's modulus, and the isotropic shear modulus are presented. In order to gain further information, the pressure and temperature-dependent behavior of the volume, the bulk modulus, the thermal expansion coefficient, the heat capacity, the entropy, Debye temperature and Gruneisen parameter are also evaluated over a pressure range of 0-6 GPa and a wide temperature range of 0-1800 K. The obtained results are in agreement with the available experimental and the other theoretical values.

WOS: 000308769000034, We have performed a first principles study of structural, mechanical, electronic, and optical properties of orthorhombic Sb2S3 and Sb2Se3 compounds using the density functional theory within the local density approximation. The lattice parameters, bulk modulus, and its pressure derivatives of these compounds have been obtained. The second-order elastic constants have been calculated, and the other related quantities such as the Young's modulus, shear modulus, Poisson's ratio, anisotropy factor, sound velocities, Debye temperature, and hardness have also been estimated in the present work. The linear photon-energy dependent dielectric functions and some optical properties such as the energy-loss function, the effective number of valence electrons and the effective optical dielectric constant are calculated. Our structural estimation and some other results are in agreement with the available experimental and theoretical data. (C) 2012 Elsevier Masson SAS. All rights reserved.

WOS: 000301629500009, To understand deeply the structural, elastic and thermodynamic characteristics of Al2X (X= Sc, Y) compounds in C15 type (space number 227) Cu2Mg structure, we have performed ab-initio density functional theory within the local density approximation (LDA) and the generalized gradient approximation (GGA). The thermodynamic properties of the considered structures are obtained through the quasi-harmonic Debye model. We have presented the results on the basic physical parameters, such as the lattice constant, bulk modulus, pressure derivative of bulk modulus, second-order elastic constants, Zener anisotropy factor, Poisson's ratio, Young's modulus, and isotropic shear modulus: In order to gain further information, the pressure- and temperature-dependent behaviour of the volume, bulk modulus, thermal expansion coefficient, heat capacity, entropy, Debye temperature and Gruneisen parameter were also evaluated over a pressure range of 0-20 GPa for Al2Sc and 0-17 GPa for Al2Y compound and a wide temperature range of 0-2000 K for both compounds. The obtained results were compared with the other reported values.

WOS: 000288043700027, The structural, electronic, and optical properties of CdxZn1-xSe alloys are investigated using the first-principles plane-wave pseudopotential method within the LDA approximations. In particular, the lattice constant, bulk modulus, electronic band structures, density of state, and optical properties such as dielectric functions, refractive index, extinction coefficient and energy loss function are calculated and discussed. Our results agree well with the available data in the literature., Turkish Prime Ministry State Planning Agency [2001K120590], This work was supported by the Turkish Prime Ministry State Planning Agency under Projects No. 2001K120590.

WOS: 000287167700076, We have studied structural, elastic, and lattice dynamical properties of the LuB2, LuB4, and LuB12 compounds by using the plane-wave pseudopotential approach to the density-functional theory within the generalized gradient approximation. We have considered three different crystal structures of LuBx: LuB2 (P6/mmm), LuB4 (P4/mbm), and LuB12 (Fm-3m). The most stable structure is found to be tetragonal (P4/mbm) structure. The comparative results on the basic physical parameters such as lattice constants, bulk modulus, bond distances, elastic constants, shear modulus, Young's modulus, and Poison's ratio are reported. Also, we have predicted that LuB4 and LuB12 compounds are potential superhard materials. Furthermore, the phonon dispersion curves and corresponding phonon density of states (DOS) are computed for considered phases. Our structural and some other results are in agreement with the available experimental and other theoretical data, Gazi University Research-Project Unit [05/2009-55], This work is supported by Gazi University Research-Project Unit under Project No: 05/2009-55.

WOS: 000287167500034, In this work, density functional theory calculations on the structural, mechanical, lattice dynamical, and thermodynamical properties of YB2 in AlB2-type and monoclinic (C2/m) structures are reported. The local density approximation has been used for modeling exchange-correlation effects. We have predicted the lattice constants, bulk modulus, elastic constants, shear modulus, Young's modulus, Poison's ratio, Debye temperature, and sound velocities. Furthermore, the phonon dispersion curves, corresponding phonon density of states, some thermodynamical quantities such as internal energy, entropy, heat capacity, and their temperature-dependent behaviors are presented. Our structural and some other results are in agreement with the available experimental and theoretical data., Gazi University Research-Project Unit [05/2009-55], This work is supported by Gazi University Research-Project Unit under Project No: 05/2009-55.

WOS: 000295492200011, We have performed the first principles calculation by using the plane-wave pseudopotential approach with the generalized gradient approximation for investigating the structural, electronic, and elastic properties Na-As systems (NaAs in NaP, LiAs and AuCu-type structures, NaAs2 in MgCu2-type structure, Na3As in Na3As, Cu3P and Li3Bi-type structures, and Na5As4 in A(5)B(4)-type structure). The lattice parameters, cohesive energy, formation energy, bulk modulus, and the first derivative of bulk modulus (to fit to Murnaghan's equation of state) of the related structures are calculated. The second-order elastic constants and the other related quantities such as Young's modulus, shear modulus, Poisson's ratio, sound velocities, and Debye temperature are also estimated. (C) 2011 Elsevier Ltd. All rights reserved.

WOS: 000287047500017, In this work, a first-principles study on PrAg compound using the density functional theory implemented in the projector-augmented wave (PAW) method in the CsCl (B2) crystal structure has been performed. Based on the optimized structural parameter, which is in good agreement with experimental data, the electronic structure, elastic, thermodynamics and vibrational properties have been investigated. The temperature and pressure variations of volume, bulk modulus, thermal expansion coefficient, heat capacities, and Debye temperatures in wide pressure (0-30 GPa) and temperature ranges have also been predicted. (C) 2010 Elsevier B.V. All rights reserved., Gazi University [05/2009-55], This work was supported by Gazi University Research-Project Unit under Project no. 05/2009-55.

WOS: 000294099900020, First principles calculations are performed to investigate the structural, elastic, and mechanical properties of CdN for various structures: NaCl, CsCl, ZnS, wurtzite, WC, CdTe, NiAs, and CuS. The local density and generalized gradient approximations are used for modeling exchange-correlation effects. Our calculations indicate that CuS (B18) structure is energetically the most stable among the considered structures. The some basic physical properties such as lattice parameters, bulk modulus, and second-order elastic constants are calculated. We have also predicted the shear modulus, Young's modulus, Poison's ratio, Debye temperature, and sound velocities. Our structural and some other results are consistent with the available theoretical data.

WOS: 000285657600013, To investigate the structural, elastic, and lattice dynamical properties of the germanium diiodide, we have performed the first-principles calculations by using the local density approximation method based on density-functional theory. Some basic physical parameters such as lattice constant, bulk modulus and its first derivatives, elastic constants, shear modulus, Young's modulus, and Poisson's ratio are calculated. The phonon dispersion curves, electronic band-structures, and total and partial density of states have also been calculated for ground state C6 phase of GeI2. Our results show that this structure has got 1.72 eV direct band gap. Our secondary results on the temperature-dependent behavior of thermodynamical properties such as entropy, heat capacity, internal energy, and free energy are also presented for the same compounds. The obtained results are in good agreement with the available experimental and other theoretical data., Gazi University Research Project Unit [05/2009/55], This work is supported by Gazi University Research Project Unit under Project No. 05/2009/55. The authors thank to Mrs. Mesude Bayrakci for technical support.

WOS: 000279295300021, The lattice dynamical calculations have been performed on the L1(2)-type (space number 221) of intermetallic compound Rh3Hf using the ab initio density-functional theory within the local density approximation (LDA) and the generalized gradient approximation (GGA). Beside the basic physical parameters such as lattice constant, bulk modulus, elastic constants, shear modulus, Young's modulus, and Poison's ratio; the phonon dispersion curves and corresponding one-phonon density of states (DOS) are also calculated for the same compound. The temperature and pressure variations of the volume, bulk modulus, thermal expansion coefficient, heat capacity, and Debye temperature in a wide pressure (0-180 GPa) and temperature (0-2000 K) ranges are presented in this study. In particular, our structural parameters (the lattice constant and bulk modulus) are consistent with the available experimental and other theoretical data., Gazi University [05/2009-55], This work is supported by Gazi University Research-Project Unit under Project No: 05/2009-55.

WOS: 000278029900005, The structural, electronic, mechanical, and vibrational properties of 4d transition metal mononitride, RhN, are investigated using the norm-conserving pseudopotentials within the local density approximation (LDA) in the frame of density functional theory. The calculated lattice parameters and the bulk modulus almost agree with the previous theoretical values. The second-order elastic constants have been calculated and the other related quantities such as Young's modulus, shear modulus, anisotropy factor, sound velocities, and Debye temperature also estimated. Charge distributions and density of states are reported to understand the bonding character in the stable phases. We have also obtained the phonon dispersion curves without LO/TO splitting., Gazi University [05/2009-55], This work is supported by Gazi University Research-Project Unit under Project No: 05/2009-55. Finally, we kindly acknowledge Dr. Savas Berber for helping on the charge-density calculations.

WOS: 000272413800011, Due to the attractive high-temperature physical properties, platinum metal-base alloys such as Rh-base alloys make them important materials for various technological applications. To understand deeply the structural, thermo-elastic, and lattice dynamical properties of the L1(2)-type (space number 221) of intermetallic compounds Rh3Ti and Rh3V, we have performed ab-initio density-functional theory within the local density approximation (LDA). Specifically, the phonon dispersion curves and corresponding one-phonon density of states (DOS) for both compounds are computed. Some basic physical parameters such as lattice constant, bulk modulus, elastic constants, shear modulus, Young's modulus, and Poison's ratio are also calculated. Our structural results are consistent with the available experimental and other theoretical data. We have also predicted the temperature and pressure variation of the volume, bulk modulus, thermal expansion coefficient, heat capacity, and Debye temperature in a wide pressure (0-80 GPa) and temperature (0-2000 K) ranges., Gazi University Research-Project Unit [05/2008-42], This work is supported by Gazi University Research-Project Unit under Project No: 05/2008-42.

WOS: 000277675400001, The results are presented of first-principles calculations of the structural, elastic and lattice dynamical properties of GdX (X = Bi, Sb). In particular, the lattice parameters, bulk modulus, phonon dispersion curves, elastic constants and their related quantities, such as Young's modulus, Shear modulus, Zener anisotropy factor, Poisson's ratio, Kleinman parameter, and longitudinal, transverse and average sound velocities, were calculated and compared with available experimental and other theoretical data. The temperature and pressure variations of the volume, bulk modulus, thermal expansion coefficient, heat capacities, Gruneisen parameter and Debye temperatures were predicted in wide pressure (0-50 GPa) and temperature ranges (0-500 K). The plane-wave pseudopotential approach to the density-functional theory within the GGA approximation implemented in VASP (Vienna ab initio simulation package) was used in all computations., Turkish Prime Ministry State Planning Agency [2001K120590], This work was supported by the Turkish Prime Ministry State Planning Agency under Projects No. 2001K120590 and we kindly acknowledge Prof. Dr Suleyman Ozcelik for his financial support.

WOS: 000286041300003, In this work density functional theory calculations on the shear products. Young modulus, poisssons ratio, hardness, structural mechanical and dynamical properties of Debye temperature and sound develocities of this compound. Re2C without B-type structure are reported. The general Furthermore the band structure phonon disperssion curvesized gadient approximation has been used for modeling and corresponding density of states are computed. The ob-change-correlation effects. We have predicted the latice and results are in good agreement with the available ex-constants bulk modulus bond distances elastic constants permiental and other theoritical data., Gazi University [05/2009-55], This work is supported by Gazi University Research-Project Unit under Project No. 05/2009-55.

WOS: 000257450300008, We have studied structural, thermodynamic, elastic, and electronic properties of platinum carbide (PtC) in zinc-blende and rock-salt structures by performing ab initio calculations within the LDA approximations. Particularly, we have focused on the structural and the pressure dependence of elastic moduli and related quantities. The other basic key properties, such as the lattice constant, cohesive energy, the phase transition pressure, bulk modulus and its pressure derivative are also repeated and compared with the other available experimental and theoretical works. (c) 2008 Elsevier B.V. All rights reserved.

WOS: 000258317600005, In this study, we have studied the structural, elastic, electronic, thermodynamical, and vibrational properties of LaBi by performing ab initio calculations within the local-density approximation (LDA). In particular, the lattice constant, bulk modulus, cohesive energy, phase transition pressure (P-t) from the NaCl (B1) to the CsCl (B2) structure, second-order elastic constants (C-ij), electronic band structures, and lattice dynamical properties were calculated and compared with the available experimental and other theoretical values. In order to obtain further information, we have also predicted Young's modulus (E), Poisson's ratio (v), the anisotropy factor (A), sound velocities, Debye temperature (theta(D)), and their pressure-dependent behaviour in the B1 phase. In addition, we have estimated the temperature-dependent behaviour of some thermodynamical properties, such as entropy and heat capacity from the lattice dynamical data.

We have Studied some Structural, thermodynamic, elastic, and electronic properties of pyrite-type SnO2 polymorph by performing ab initio calculations within the LDA approximation. The basic physical properties, in particular lattice constant, bulk modulus, secondorder clastic constants (C-ij), and the electronic structure, are calculated, and compared with the available experimental data. In order to gain some further information on the mechanical properties, we have also calculated the Young's modulus, Poison's ratio (nu), anisotropy factor (A), Sound velocities, and Debye temperature for the same compound. (C) 2007 Elsevier Ltd. All rights reserved.

We present the results of ab-initio study on the structural, elastic, thermodynamics, and electronic properties of the nonmagnetic Lanthanum nitride (LaN) using the plane-wave pseudopotential approach to the density-functional theory within the generalized-gradient approximation implemented in VASP (Viena Ab-initio Simulation Package). The calculated structural parameters (the lattice constant, bulk modulus, cohesive energy), the phase transition pressure from NaCl (B1) to CsCl (B2) phase, elastic constants, Zener anisotropy factor (A), Poisson ratio (nu), Young's modulus (Y), Shear modulus (C'), Debye temperature, and band structures are presented. The obtained results are compared with the available experimental and the other theoretical results. (C) 2007 Elsevier B.V. All rights reserved.

We have studied the structural, elastic, electronic, thermodynamical and vibrational properties of LaAs and LaP in the rock-salt (B1) structure by performing ab initio calculations within the local-density approximation (LDA). Some basic physical properties, such as the lattice constant, bulk modulus, cohesive energy, second-order elastic constants (C-ij), the electronic band structures, and phonon frequencies, are calculated and compared with the available experimental and other theoretical values. In order to gain further information, we have, also, predicted the Young's modulus, Poisson's ratio (nu), anisotropy factor ( A), sound velocities, and Debye temperature (theta(D)), and reasonable values have been found. We also present the temperature-dependent behaviour of some thermodynamical properties such as entropy and heat capacity for these compounds in the B1 phase.