First Principles Calculation of Oxygen Ordering in YBa2Cu3O7-y

ABSTRACTWe have performed a number of first principles electronic structure calculations for YBa 2Cu 3O7_y with different oxygen orderings and concentrations. The resulting total energies have been used to assess the applicability of some of the proposed models for oxygen ordering in this system. We find that the results are consistent with an Ising-like model with asymmetric next-neighbor interactions between oxygen sites. We determine effective interaction parameters from the first principles calculations and use them to compute the phase diagram for the system, which is in excellent agreement with experiment for the tetragonal-orthorhombic I transition.

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Site-by-Site Electronic Structure Analysis of Al-Containing Complex Compounds Using Channeling EELS and First Principles Calculations

Materials Science Forum ◽

10.4028/www.scientific.net/msf.561-565.2091 ◽

2007 ◽

Vol 561-565 ◽

pp. 2091-2094

Author(s):

Kazuyoshi Tatsumi ◽

Yu Yamamoto ◽

Shunsuke Muto

Keyword(s):

Electronic Structure ◽

Structure Analysis ◽

First Principles ◽

Electronic Structure Calculations ◽

Complex Compounds ◽

Oxide Ceramics ◽

First Principles Calculations ◽

Spectral Difference ◽

Curve Resolution ◽

Structure Calculations

Al K ELNES of oxide ceramics, which show reverse spinel and garnet structures containing two types of Al sites, are investigated site-selectively using TEM-EELS under electron channeling conditions. We applied a self-modeling curve resolution (SMCR) technique to separate a set of experimental spectra into individual spectra of individual atomic sites. The refined spectra after SMCR were in consistent with the theoretical spectra obtained by the first principles electronic structure calculations. The spectral difference of the six-coordinated aluminum between the two materials was discussed in terms of the cationic coordination.

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First-Principles Calculations of Electronic Structure and Structural Properties for MoV, MoNb, and MoTa

MRS Proceedings ◽

10.1557/proc-646-n5.33.1 ◽

2000 ◽

Vol 646 ◽

Cited By ~ 2

Author(s):

R. de Coss ◽

A. Aguayo ◽

G. Murrieta

Keyword(s):

Electronic Structure ◽

Melting Point ◽

Bulk Modulus ◽

First Principles ◽

Electronic Structure Calculations ◽

Full Potential ◽

First Principles Calculations ◽

Augmented Plane Wave ◽

Linearized Augmented Plane Wave ◽

Structure Calculations

ABSTRACTFirst-principles total-energy electronic structure calculations based on the full-potential linearized augmented plane wave (LAPW) method have been used to study the electronic and elastic properties of MoV, MoNb, and MoTa with the B2 (CsCl) estructure. From the calculated values for the bulk modulus we have determined the melting temperature using an empirical correlation. The chemical bond and the electronic structure around the Fermi level are analyzed. In particular, we found that MoTa which have the experimental determined highest melting point of the studied materials, present the largest bulk modulus and the highest degree of covalence bonding of these intermetallic compounds.

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Mechanical and Electronic Properties of P42/mnm Silicon Carbides

Zeitschrift für Naturforschung A ◽

10.1515/zna-2015-0539 ◽

2016 ◽

Vol 71 (5) ◽

pp. 387-396 ◽

Cited By ~ 9

Author(s):

Quan Zhang ◽

Qun Wei ◽

Haiyan Yan ◽

Qingyang Fan ◽

Xuanmin Zhu ◽

...

Keyword(s):

Density Functional Theory ◽

Electronic Structure ◽

Electronic Properties ◽

First Principles ◽

Density Functional ◽

Electronic Structure Calculations ◽

First Principles Calculations ◽

Functional Theory ◽

Silicon Carbides ◽

Structure Calculations

AbstractTwo new phases of Si8C4 and Si4C8 with the P42/mnm symmetry are proposed. Using first principles calculations based on density functional theory, the structural, elastic, and electronic properties of Si8C4 and Si4C8 are studied systematically. Both Si8C4 and Si4C8 are proved to be mechanically and dynamically stable. The elastic anisotropies of Si8C4 and Si4C8 are studied in detail. Electronic structure calculations show that Si8C4 and Si4C8 are indirect semiconductors with the band gap of 0.74 and 0.15 eV, respectively.

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Electronic Structure Calculations of Electronic and Structural Properties of Plutonium 115 Compounds

MRS Proceedings ◽

10.1557/proc-0893-jj02-01 ◽

2005 ◽

Vol 893 ◽

Author(s):

John Wills ◽

Raquel Lizarraga ◽

John J. Joyce ◽

Tomasz Durakiewicz ◽

John L. Sarrao ◽

...

Keyword(s):

Electronic Structure ◽

Structural Properties ◽

Electron Correlation ◽

First Principles ◽

Electronic States ◽

Electronic Structure Calculations ◽

First Principles Calculations ◽

Level Model ◽

Electronic And Structural Properties ◽

Structure Calculations

AbstractThe 5f electronic states in elemental Pu and Pu compounds exhibit elements of both itinerant and localized behavior. Several first-principles calculations have been presented to describe this balance, differing in the manner in which electron correlation is included in the calculation. This paper describes a calculations performed with the Mixed Level Model (MLM), presenting calculated results for the two Pu compounds, PuRhGa5 and PuCoGa5. The MLM results are compared with other calculations and the differences discussed.

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Effect of Boron and Hydrogen on the Electronic Structure of Ni3Al

MRS Proceedings ◽

10.1557/proc-319-363 ◽

1993 ◽

Vol 319 ◽

Cited By ~ 2

Author(s):

N. Kioussis ◽

H. Watanabe ◽

R.G. Hemker ◽

W. Gourdin ◽

A. Gonis ◽

...

Keyword(s):

Electronic Structure ◽

Charge Density ◽

First Principles ◽

Electronic Structure Calculations ◽

Interstitial Site ◽

Octahedral Interstitial Site ◽

Interstitial Region ◽

Ordered Intermetallic ◽

Lmto Method ◽

Structure Calculations

AbstractUsing first-principles electronic structure calculations based on the Linear-Muffin-Tin Orbital (LMTO) method, we have investigated the effects of interstitial boron and hydrogen on the electronic structure of the L12 ordered intermetallic Ni3A1. When it occupies an octahedral interstitial site entirely coordinated by six Ni atoms, we find that boron enhances the charge distribution found in the strongly-bound “pure” Ni3AI crystal: Charge is depleted at Ni and Al sites and enhanced in interstitial region. Substitution of Al atoms for two of the Ni atoms coordinating the boron, however, reduces the interstitial charge density between certain atomic planes. In contrast to boron, hydrogen appears to deplete the interstitial charge, even when fully coordinated by Ni atoms. We suggest that these results are broadly consistent with the notion of boron as a cohesion enhancer and hydrogen as an embrittler.

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Stability and Structures of Constitutional Defects in Nonstoichiometric Intermetallic Compounds by First-Principles Calculations

Materials Science Forum ◽

10.4028/www.scientific.net/msf.475-479.3111 ◽

2005 ◽

Vol 475-479 ◽

pp. 3111-3114

Author(s):

Masataka Mizuno ◽

Hideki Araki ◽

Yasuharu Shirai

Keyword(s):

Intermetallic Compounds ◽

First Principles ◽

Electronic Structures ◽

Stoichiometric Composition ◽

Electronic Structure Calculations ◽

First Principles Calculations ◽

Compositional Dependence ◽

Wide Range ◽

Formation Energies ◽

Structure Calculations

Some of intermetallic compounds exist in a wide range of concentration around the stoichiometric composition. First-principles electronic structure calculations have been performed for constitutional defects in non-stoichiometric CoAl and CoTi in order to investigate their stabilities and structural relaxations induced by constitutional defects. For the evaluation of stabilities of constitutional defects, the compositional dependence curves both of formation energies and of lattice parameters are obtained by the calculations employing supercells in various sizes. The lattice relaxations around constitutional defects are discussed by analyzing the change in electronic structures induced by constitutional defects.

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