Results of self-consistent band-structure calculations for ScN, ScO, TiC, TiN, TiO, VC, VN and VO

Neckel, A.; Rastl, P.; Eibler, R.; Weinberger, P.; Schwarz, K.

doi:10.1088/0022-3719/9/4/008

Cited by 393 publications

(136 citation statements)

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“…The deep minimum present -8 eV above the threshold in the 3d compounds also becomes less significant. This is consistent with the band structure calculations of Neckel and co-workers; the band structure of TiC shows a band-gap at a similar energy above the Fermi level [11] whereas that for NbC shows no bandgap in this region [12]. Figure 2, the spectra are shown with an expanded energy scale and reordered to facilitate comparison of compounds with metal species from the same transition series.…”

Section: Resultssupporting

confidence: 87%

Electron Energy Loss Near Edge Structure (ELNES) on the Carbon K-Edge in Transition Metal Carbides with the Rock Salt Structure

Craven

Garvie

1995

Microsc. Microanal. Microstruct.

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Section: Resultssupporting

confidence: 87%

Electron Energy Loss Near Edge Structure (ELNES) on the Carbon K-Edge in Transition Metal Carbides with the Rock Salt Structure

Craven

Garvie

1995

Microsc. Microanal. Microstruct.

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“…The results shown that the optic modes could differ by 3.5%, while the acoustic modes are less sensitive to carbon content. The elastic constants derived from the measured acoustic dispersion curves agree very well with those obtained by ultrasonic measurements for TiC 0.91 crystal [3].Very interesting properties and simple structure of TiC caused that efforts to understand its properties using firstprinciple calculations have been undertaken several times [4,5,6,7]. The electronic structure, bulk modulus, and elastic constants have been found [8] by means of accurate first-principles total-energy calculations using the full potential linear muffin-tin orbital method.…”

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confidence: 66%

TiC lattice dynamics from ab initio calculations

Jochym¹,

Parliński²,

Sternik³

1999

Eur. Phys. J. B

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Abstract. Ab initio calculations and a direct method have been applied to derive the phonon dispersion curves and phonon density of states for the TiC crystal. The results are compared and found to be in a good agreement with the experimental neutron scattering data. The force constants have been determined from the Hellmann-Feynman forces induced by atomic displacements in the 2×2×2 supercell. The calculated phonon density of states suggests that vibrations of Ti atoms form acoustic branches, whereas the motion of C atoms is confined to optic branches. The elastic constants have been found using the deformation method and compared with the results obtained from acoustic phonon slopes. The transition-metal carbide compounds, of which TiC is a representative, are of big scientific and technological interest because of their striking mechanical properties, extreme hardness combined additionally with metallic electrical and thermal conductivity. They have usually a rock-salt crystal structure -like some ionic crystalswhile having properties typical for materials with covalent bonding. It suggests that the bonding have some mixed nature, which makes these materials very interesting as an object of study. PACSOver a large range of fractional carbon content from TiC to TiC 0.5 [1] the TiC is stable in the NaCl structure, with space group Fm3m. In practice, it is usually nonstoichiometric and contains carbon vacancy defects. The phonon dispersion curves of nearly stoichiometric TiC 0.95 have been measured along main symmetry directions by Pintschovius et al [2] using the inelastic neutron scattering technique. In the same paper, the influence of the carbon content on the phonon dispersion curves has been additionally checked by measuring a sample with lower carbon concentration TiC 0.89 . The results shown that the optic modes could differ by 3.5%, while the acoustic modes are less sensitive to carbon content. The elastic constants derived from the measured acoustic dispersion curves agree very well with those obtained by ultrasonic measurements for TiC 0.91 crystal [3].Very interesting properties and simple structure of TiC caused that efforts to understand its properties using firstprinciple calculations have been undertaken several times [4,5,6,7]. The electronic structure, bulk modulus, and elastic constants have been found [8] by means of accurate first-principles total-energy calculations using the full potential linear muffin-tin orbital method. The calculated In this paper we intend to extend first-principle calculations to describe the phonon dispersion curves and phonon density of TiC. The method which was is based on the total energy calculation and Hellmann-Feynman (HF) forces. Dispersion relations are calculated by direct method [9,10,11,12,13], in which the force constants of the dynamical matrix are calculated from HF forces. Elastic constants and bulk modulus have been estimated by straight evaluation of energy derivatives with respect to deformation.The energies and forces of the TiC crystal were calcu...

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“…The elastic constants are found using the deformation method and successfully compare with experimental data. [4,5,6,7]. The electronic structure, bulk modulus, and elastic constants, as well as the phonon dispersion relations have been found for TiC, TiN and TiO compounds by means of first-principles totalenergy calculations [8,9].…”

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confidence: 99%

Ab initio lattice dynamics and elastic constants of ZrC

Jochym

Parliński

2000

Eur. Phys. J. B

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Abstract. Ab initio calculations and a direct method are applied to derive the phonon dispersion relations and phonon density of states for the ZrC crystal. The results are in good agreement with neutron scattering data. The force constants are determined from the Hellmann-Feynman forces induced by atomic displacements in a 2×2×2 supercell. The elastic constants are found using the deformation method and successfully compare with experimental data. [4,5,6,7]. The electronic structure, bulk modulus, and elastic constants, as well as the phonon dispersion relations have been found for TiC, TiN and TiO compounds by means of first-principles totalenergy calculations [8,9]. Generally, the calculated values show good agreement with experiments. This provides a motivation to extend the investigation to heavier transition metals and to treat zirconium carbide, ZrC. This crystal is an important material in nuclear energy technology, since it provides a filling medium for fuel particles. It is also used for surface hardening and coverage of cathodes of X-ray sources. In this paper we continue to study the lattice dynamics and elastic properties of transition-metal compounds. See [8] and references given there for a more detailed description of the method. PACSThe transition-metal carbide compounds, of which ZrC is a representative, are of considerable scientific and technological interest because of their striking mechanical properties, extreme hardness combined with metallic electrical and thermal conductivities. The ZrC crystal has NaCl structure and it is usually non-stoichiometric, mainly owing to carbon-vacancy defects. The phonon dispersion relations of ZrC have been measured along main symmetry directions by Smith et al [10,11]. Elastic constants, in turn, have been measured for two concentrations of carbon (ZrC 0.89 and ZrC 0.94 ) by Chang and Graham [12].In this paper we extend the first-principle calculations to describe the phonon dispersion curves, phonon density and elastic constants of ZrC. The method which is used, is based on the total energy calculation and HellmannCorrespondence to: jochym@ifj.edu.pl Feynman (HF) forces. The phonon dispersion relations are calculated by the direct method and the Phonon program [13,14,15,16,17,18], in which the force constants of the dynamical matrix are derived from HF forces. Alternatively, one could use the linear-response method [19,20] for the evaluation of ab initio phonon frequencies at a predetermined set of Brillouin zone points. Elastic constants and bulk modulus are estimated by straightforward evaluation of energy derivatives with respect to the deformations.The energies and HF forces of ZrC crystal are calculated by the method of total energy minimization, using norm-conserving pseudopotentials as an approximation for the atomic core-valence electron interaction [21,22,23]. This method allows to include the pressure in calculations as well as anharmonic effects. For the lattice dynamics calculations a 2×2×2 supercell with periodic boundary conditions and 64 ...

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Results of self-consistent band-structure calculations for ScN, ScO, TiC, TiN, TiO, VC, VN and VO

Cited by 393 publications

References 13 publications

Electron Energy Loss Near Edge Structure (ELNES) on the Carbon K-Edge in Transition Metal Carbides with the Rock Salt Structure

Electron Energy Loss Near Edge Structure (ELNES) on the Carbon K-Edge in Transition Metal Carbides with the Rock Salt Structure

TiC lattice dynamics from ab initio calculations

Ab initio lattice dynamics and elastic constants of ZrC

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