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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: 000454382200031, Density functional theory calculations are used herein to explore the effect of hydrogen on the electronic, mechanical and phonon properties of LaMgNi4 and its hydrides. The polycrystalline elastic moduli, Poisson's ratios and Debye temperatures are calculated based on the single-crystal elastic constants and Voigt-Reuss-Hill approximations. It is also found that all these materials are metallic behavior, ductile and anisotropic in nature. The mechanical anisotropy is discussed via several anisotropy indices and three-dimensional (3D) surface constructions. The effect of high temperature on the free energy, entropy, and heat capacity are also studied by using the quasi-harmonic Debye model. LaMgNi4 and its hydrides are found to be energetically, mechanically and dynamically stable. Also, they are thermodynamically stable and the order of phase stability is LaMgNi4H7 > LaMgNi4H4 > LaMgNi4H > LaMgNi4. In addition, the highest gravimetric hydrogen storage capacity is found to be 1.74 wt% for LaMgNi4H7. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

WOS: 000393880000002, The newly synthesised Ba2Sb4GeS10 compound is notable because of the interesting features of the quaternary Sb-containing materials. The first principle method has been used to determine the physical properties of this compound. In particular, the electronic structure has been analysed using both conventional GGA-PBE and HSE06 functional. The values of the band gap for PBE and HSE06 calculations were 1.324 and 1.84 eV, respectively. The calculated elastic constants were used to predict polycrystalline mechanical properties. The estimated Vickers hardness (2.7 GPa) values show that Ba2Sb4GeS10 is soft matter. Moreover, the vibrational properties of the compound have been studied. The calculation of the elastic constants and phonon dispersion curves indicates that the Ba2Sb4GeS10 compound is stable both mechanically and dynamically. Furthermore, the minimum thermal conductivity and optical properties, such as dielectric functions and energy loss function, have also been discussed in detail in this paper.

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: 000407392800007, In this study, we have investigated the electronic and optical properties of half-Heusler NiXSn (X = Zr, Hf) compounds under pressure by means of first principles calculations. The generalized gradient approximation is used to model exchange-correlation effects. We have estimated a transition from indirect band gap to direct band gap at 50 and 127 GPa for NiZrSn and NiHfSn, respectively. We have also plotted the static dielectric constant versus pressure for both compounds. The obtained results are in agreement with the available experimental and theoretical data.

WOS: 000395604700011, We report in this paper the synthesis, spectroscopic, crystal structure, biological activities and theoretical results of the title compound. The crystal structure was defined by the X-ray diffraction (XRD) method. In addition, this newly synthesized hydrazone derivative was also subjected to its possible antioxidant activity with free radical scavenging ability of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals using butylated hydroxytoluene (BHT) as standard antioxidant. The structural calculations were performed by the density functional theory using the B3LYP method with 6-311++G(2d,2p) basis set. The calculated values were compared with experimental results. (C) 2017 Elsevier B.V. All rights reserved., Aksaray University, Science and Technology Application and Research Center, Turkey of the State of Planning Organization [20101K120480]; Ataturk University, The authors acknowledge the Aksaray University, Science and Technology Application and Research Center, Turkey, for the use of the Bruker Smart Breeze CCD diffractometer (purchased under grant 20101K120480 of the State of Planning Organization); Dr. Bans And from Ataturk University for NMR measurements.

WOS: 000380852000080, The structural, mechanical and lattice dynamical properties of Ru2B3 and Os2B3 have been investigated by using a first-principles method based on the density functional theory within the generalized gradient approximation. The single crystal elastic constants are numerically estimated using strain-stress approach. The polycrystalline aggregate elastic parameters are calculated from the single elastic constants via the Voigt-Reuss-Hill approximations. Subsequently, the ductility and brittleness are characterized with the estimation from Pugh's rule (B/G) and Cauchy pressure. Additionally, the Debye temperature is calculated from the average elastic wave velocity obtained from bulk and shear moduli. The calculated parameters are consistent with the previous experimental and theoretical data. These borides are both mechanically and dynamically stable in the considered structure.

WOS: 000377049700011, Electronic structure and optical properties of the CdXO3 and ZnXO3 (XGe, Sn) compounds have been investigated based on density functional theory. According to the predictive results, reveal that the CdXO3 and ZnXO3 would be candidates for a high performance lead free optical crystal, which will avoid the environmental toxicity problem of the lead-based materials., project DPT-HAMIT; project DPT-FOTON; project NATO-SET [193]; project TUBITAK [113E331, 109A015, 109E301]; Turkish Academy of Sciences, This work is supported by the projects DPT-HAMIT, DPT-FOTON, NATO-SET-193 and TUBITAK under Project Nos., 113E331, 109A015, 109E301. One of the authors (Ekmel Ozbay) also acknowledges partial support from the Turkish Academy of Sciences. The numerical calculations reported in this paper were fully performed at Aksaray University, Science and Technology Application and Research Center.

WOS: 000358148500004, The first-principles calculations are employed to provide a fundamental understanding of the structural features and relative thermodynamical, mechanical and phonon stability of TiAsTe compound. The calculated lattice parameters are in good agreement with available experimental results. We have computed elastic constants, its derived moduli and ratios that characterize mechanical properties for the first time. The calculated elastic constants indicate that these materials are mechanically stable at ambient condition. The minimum thermal conductivities of TiAsTe are calculated using both Clarke's model and Cahill's model. Furthermore, the elastic anisotropy has been visualized in detail by plotting the directional dependence of compressibility, Young's modulus and shear modulus. Our results suggest strong elastic anisotropy for this compound. Additionally, the phonon spectra and phonon density of states are also obtained and discussed. The full phonon dispersion calculations confirm the dynamic stability of TiAsTe.

WOS: 000361774100016, In this study, sol-gel spin coating route was carried out to prepare Scandium doped ZnO thin films with different controlled percentage (1-7%). Particularly, it has been demonstrated, through original conjoint morphological-structural and optical investigations, that some interesting physical properties were induced. Indeed, X-ray diffraction (XRD) analysis shows that (002) preferential crystalline plane for Sc doped ZnO films was kept along with ZnO hexagonal wurtzite structure, although Sc doping seemed to cause a decrease in crystallinity. Except for 1 at% Sc doping ratio, optical band gap changes reversely with Urbach energy with a decrease in optical gap and a broadening of the absorption tail. Ab-initio calculations of lattice dynamical properties outlined additional strong hybridization between Sc and O atoms and show the stability of Scandium doped ZnO.

20th International Conference on Ternary and Multinary Compounds (ICTMC) -- SEP 05-09, 2016 -- Halle, GERMANY, WOS: 000405267800024, In present work, our research is mainly focused on the electronic structures, optical, and magnetic properties of XMnSb (X = Ni, Cu, Pd), Co(2)YZ (Y = Ti; Z = Si, Ge, Sn), and Co(2)YZ (Y = Mn; Z = Al, Ga, Si) Heusler compounds by using ab initio calculations within the generalized gradient approximation. The calculations are performed by using the Vienna ab initio simulation package based on the density functional theory. The band structure of these Heusler alloys for majority spin and minority spin were calculated and the majority spin states cross the Fermi level and thus have the metallic character, while the minority spin states open the band gaps around the Fermi level and thus have the narrow-band semiconducting nature. We also find that these Heuslercompounds have the indirect band gaps in the minority spin channel. The real and imaginary parts of dielectric functions and hence the optical functions such as energy-loss function, the effective number of valance electrons and the effective optical dielectric constant for XMnSb and Co2YZ compounds were also calculated. In addition, we also show the variations of the total magnetic moment per f.u. and minority spin gap width of these compounds with optimized lattice constants: minority spin gap width decreases with increasing the lattice constants.

WOS: 000335865100001, We have investigated the structural, mechanical and lattice dynamical properties of ZrW2 and HfW2 compounds in cubic C15 (space group Fd-3m), hexagonal C14 (space group P6(3)/mmc) and C36 (space group P6(3)/mmc) phases using generalized gradient approximation within the plane-wave pseudo-potential density functional theory. We have found that ZrW2 and HfW2 in cubic C15 phase are the most stable among the considered phases. From calculated elastic constants, it is shown that all phases are mechanically stable according to the elastic stability criteria. The related mechanical properties, such as bulk, shear and Young moduli, Poisson's ratio, Debye temperature and hardness have been also calculated. The results show that ZrW2 and HfW2 compounds are ductile in nature with respect to the B/G and Cauchy pressure analysis. The phonon dispersion curves, phonon density of states and some thermodynamic properties are computed and discussed exhaustively for considered phases.

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: 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: 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: 000313561600005, In the framework of density functional theory, the structural, lattice dynamical and thermodynamical properties of the C15-type of Al2Ca and Al2Mg compounds are investigated. The calculated lattice constants are in good agreement with the other works. The results show that these compounds are dynamically stable in the considered structure. The temperature dependence of the various thermodynamical quantities such as internal energy, free energy, entropy, and heat capacity are also predicted within the harmonic approximation, and the observed trends are discussed in detail. (C) 2012 Elsevier B.V. All rights reserved.

WOS: 000313561600044, We have tried to theoretically predict the lattice dynamical and thermodynamic properties of rare earth diborides (XB2, X = Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm) in AlB2-type structure based on density functional theory within generalized gradient approximation. The calculated equilibrium lattice parameters are in overall agreement with the available experiment and other theoretical results. The phonon dispersion curves are derived by using the direct method. The lattice dynamical results are showed that these compounds are dynamically stable for the considered structure, and these properties exhibits, almost, similar trend for these compounds. In addition, thermodynamic properties such as the free energy, enthalpy, entropy and heat capacity are, also successfully predicted and analyzed with the help of phonon dispersion. (C) 2012 Elsevier B. V. All rights reserved.

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: 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: 000299703800016, The conformational analysis of rasagiline [N-propargyl-1(R)-aminoindan] was performed by the density functional theory (DFT) B3LYP method using the 6-31++G (d,p) basis set. A single point energy calculations based on the B3LYP optimized geometries were also performed at MP2/6-31++G (d, p) level. The vibrational frequencies of the most stable conformer of rasagiline was calculated at the B3LYP level and vibrational assignments were made for normal modes on the basis of scaled quantum mechanical force field (SQM) method. The influence of mesylate and ethanedisulfonate salts on the geometry of rasagiline free base and its normal modes are also discussed.

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: 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: 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: 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: 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.

7th International Conference of the Balkan-Physical-Union -- SEP 09-13, 2009 -- Alexandroupolis, GREECE, WOS: 000281467300224, The conformational equilibrium of triclosan (5-chloro-2-(2, 4-dichlorophenoxy) phenol) have been calculated using density functional theory (DFT/B3LYP/6-311++G(d,p)) method. Four different geometries were found to correspond to energy minimum conformations. The IR spectrum of triclosan was measured in the 4000-400 cm(-1) region We calculated the harmonic frequencies and intensities of the most stable conformers in order to assist in the assignment of the vibrational bands in the experimental spectrum The fundamental vibrational modes were characterized depending on their total energy distribution (TED%) using scaled quantum mechanical (SQM) force field method., Balkan Phys Union, Helen Phys Soc, Univ Crete, Univ Athens, Univ Ioannina, Univ Petras, Univ Thessaloniki, TEAK, Prefecture Evros, Reg Adm Eastern Macedonia & Thrace

WOS: 000261972300004, The molecular geometry, the normal mode frequencies and corresponding vibrational assignments of methylphenidate in the ground state were performed by DFT/B3LYP level of theory using the 6-311++G(d, p) basis set. Harmonic vibrational frequencies were calculated. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The conformational stabilities and optimized geometrical parameters have been carried out with density functional theory with 6-311++G(d,p) basic set by the DFT/B3LYP method. The frequency calculations have been performed with DFT to study the vibrational properties and their dependence on the molecular conformation. (C) 2008 Elsevier B.V. All rights reserved., Gazi University [05/2007-22], This work was supported by Gazi University, BAP Research Projects, and No. 05/2007-22.

WOS: 000302790300067, The structural, electronic and elastic properties of Rb-As systems (RbAs in NaP, LiAs and AuCu structures, RbAs2 in the MgCu2 structure, Rb3As in Na3As, Cu3P and Li3Bi structures, and Rb5As4 in the A(5)B(4) structure) are investigated with the generalized gradient approximation in the frame of density functional theory. The lattice parameters, cohesive energies, formation energies, bulk moduli and the first derivatives of the bulk moduli (to fit Murnaghan's equation of state) of the considered structures are calculated and reasonable agreement is obtained. In addition, the phase transition pressures are also predicted. The electronic band structures, the partial densities of states corresponding to the band structures and the charge density distributions are presented and analysed. The second-order elastic constants based on the stress-strain method and other related quantities such as Young's modulus, the shear modulus, Poisson's ratio, sound velocities, the Debye temperature and shear anisotropy factors are also estimated.

WOS: 000287917200016, A detailed theoretical study of the structural, elastic and vibrational properties of DyX (X = P, As) compounds is presented in this paper by performing ab initio calculations based on density functional theory using the VASP code. For describing the interaction between electrons and ions, the projector-augmented wave method is used. The generalized-gradient approximation is chosen for the exchange-correlation functional. The calculated structural parameters, such as the lattice constant, bulk modulus and second-order elastic constants, are presented. The high-pressure phase of both compounds is investigated and the phase transition pressure from NaCl (B1) to high-pressure phase (B2) is determined. To gain further information, we have calculated the 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 the B1 structure of these compounds. The temperature-dependent variations of some thermodynamic properties such as entropy, heat capacity, internal energy and free energy are also predicted for the same compounds in the B1 phase., Gazi University [05/2010-51], This work was supported by Gazi University Research-Project Unit under project no. 05/2010-51.