scholarly journals Electronic structures and phonon free energies of LaCoO3using hybrid-exchange density functional theory

2013 ◽  
Vol 87 (12) ◽  
Author(s):  
S. Mukhopadhyay ◽  
M. W. Finnis ◽  
N. M. Harrison
Keyword(s):  
Density Functional Theory ◽  
Electronic Structures ◽  
Density Functional ◽  
Free Energies ◽  
Functional Theory

Defect-free and Defective Surfaces of the Pyrochlore Oxide La2Zr2O7: A Theoretical Study

2011 ◽  
Vol 1370 ◽  
Author(s):  
Yves A. Mantz
Keyword(s):  
Density Functional Theory ◽  
Free Energy ◽  
Electronic Structures ◽  
Density Functional ◽  
Theoretical Study ◽  
Perfect Crystal ◽  
Free Energies ◽  
Functional Theory ◽  
Lanthanum Zirconate ◽  
Pyrochlore Oxide

ABSTRACTIn this work, the low index faces of lanthanum zirconate (La2Zr2O7, LZ) are studied at the level of density-functional theory, representing the first theoretical attempt to characterize the surfaces of a pyrochlore oxide. All possible surface terminations formed by cleaving a perfect crystal are considered, as well as selected defective surfaces. After deriving the expression for the free energy of an LZ surface, surface free energies are computed. The most stable surface terminations are identified, their geometric and electronic structures discussed, and a motivation provided for calculating ratios of certain surface free energies more accurately for comparison to experimental results that will be obtained.

scholarly journals Atoms in Highly Symmetric Environments: H in Rhodium and Cobalt Cages, H in an Octahedral Hole in MgO, and Metal Atoms Ca-Zn in C20 Fullerenes

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1281
Author(s):  
Zikri Altun ◽  
Erdi Ata Bleda ◽  
Carl Trindle
Keyword(s):  
Density Functional Theory ◽  
Quantum Theory ◽  
Coordination Number ◽  
Electronic Structures ◽  
Density Functional ◽  
Functional Theory ◽  
Metal Atoms ◽  
Tetragonal Pyramidal ◽  
Non Covalent Interactions ◽  
Covalent Interactions

An atom trapped in a crystal vacancy, a metal cage, or a fullerene might have many immediate neighbors. Then, the familiar concept of valency or even coordination number seems inadequate to describe the environment of that atom. This difficulty in terminology is illustrated here by four systems: H atoms in tetragonal-pyramidal rhodium cages, H atom in an octahedral cobalt cage, H atom in a MgO octahedral hole, and metal atoms in C20 fullerenes. Density functional theory defines structure and energetics for the systems. Interactions of the atom with its container are characterized by the quantum theory of atoms in molecules (QTAIM) and the theory of non-covalent interactions (NCI). We establish that H atoms in H2Rh13(CO)243− trianion cannot be considered pentavalent, H atom in HCo6(CO)151− anion cannot be considered hexavalent, and H atom in MgO cannot be considered hexavalent. Instead, one should consider the H atom to be set in an environmental field defined by its 5, 6, and 6 neighbors; with interactions described by QTAIM. This point is further illustrated by the electronic structures and QTAIM parameters of M@C20, M=Ca to Zn. The analysis describes the systematic deformation and restoration of the symmetric fullerene in that series.

scholarly journals Na-ion diffusion in a NASICON-type solid electrolyte: a density functional study

2016 ◽  
Vol 18 (39) ◽  
pp. 27226-27231 ◽  
Author(s):  
Kieu My Bui ◽  
Van An Dinh ◽  
Susumu Okada ◽  
Takahisa Ohno
Keyword(s):  
Density Functional Theory ◽  
Solid Electrolyte ◽  
Electronic Structures ◽  
Density Functional ◽  
Diffusion Mechanism ◽  
Functional Study ◽  
Ion Diffusion ◽  
Functional Theory ◽  
Density Functional Study ◽  
Nasicon Type

Based on density functional theory, we have systematically studied the crystal and electronic structures, and the diffusion mechanism of the NASICON-type solid electrolyte Na3Zr2Si2PO12.

Probing the electronic structures of Con (n = 1–5) clusters on γ-Al2O3 surfaces using first-principles calculations

2017 ◽  
Vol 19 (5) ◽  
pp. 3679-3687 ◽  
Author(s):  
Tao Yang ◽  
Masahiro Ehara
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
First Principles Calculations ◽  
Functional Theory

Using density functional theory calculations, we discussed the geometric and electronic structures and nucleation of small Co clusters on γ-Al2O3(100) and γ-Al2O3(110) surfaces.

scholarly journals Electronic Structure and Optical Properties of Co and Fe Doped ZnO

2016 ◽  
Vol 43 ◽  
pp. 23-28 ◽  
Author(s):  
Chun Ping Li ◽  
Ge Gao ◽  
Xin Chen
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Electronic Structures ◽  
Density Functional ◽  
Band Gaps ◽  
First Principle ◽  
Functional Theory ◽  
Doped Zno ◽  
Pseudo Potential ◽  
Co Doped

First-principle ultrasoft pseudo potential approach of the plane wave based on density functional theory (DFT) has been used for studying the electronic characterization and optical properties of ZnO and Fe, Co doped ZnO. The results show that the doping impurities change the lattice parameters a little, but bring more changes in the electronic structures. The band gaps are broadened by doping, and the Fermi level accesses to the conduction band which will lead the system to show the character of metallic properties. The dielectric function and absorption peaks are identified and the changes compared to pure ZnO are analyzed in detail.

scholarly journals A Free Aluminylene with Diverse σ-Donating and Doubly σ/π-Accepting Ligand Features for Transition Metals

2021 ◽  
Author(s):  
Xin Zhang ◽  
Liu Leo Liu
Keyword(s):  
Density Functional Theory ◽  
Coordination Chemistry ◽  
Transition Metals ◽  
Electronic Structures ◽  
Ligand Exchange ◽  
Density Functional ◽  
Reduction Reaction ◽  
Functional Theory ◽  
Metal Centers ◽  
Coordination Behavior

We report herein the synthesis, characterization, and coordination chemistry of a free N-aluminylene, namely a carbazolylaluminylene 2b. This species is prepared via a reduction reaction of the corresponding carbazolyl aluminium diiodide. The coordination behavior of 2b towards transition metal centers (W, Cr) is shown to afford a series of novel aluminylene complexes 3-6 with diverse coordination modes. We demonstrate that the Al center in 2b can behave as: 1. a σ-donating and doubly π-accepting ligand; 2. a σ-donating, σ-accepting and π-accepting ligand; and 3. a σ-donating and doubly σ-accepting ligand. Additionally, we show ligand exchange at the aluminylene center providing access to the modulation of electronic properties of transition metals without changing the coordinated atoms. Investigations of 2b with IDippCuCl (IDipp = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) show an unprecedented aluminylene-alumanyl transformation leading to a rare terminal Cu-alumanyl complex 8. The electronic structures of such complexes and the mechanism of the aluminylene-alumanyl transformation are investigated through density functional theory (DFT) calculations.

Density functional theory calculations of atomic, electronic and thermodynamic properties of cubic LaCoO3and La1−xSrxCoO3surfaces

RSC Advances ◽  
2015 ◽  
Vol 5 (1) ◽  
pp. 760-769 ◽  
Author(s):  
Shuguang Zhang ◽  
Ning Han ◽  
Xiaoyao Tan
Keyword(s):  
Density Functional Theory ◽  
Thermodynamic Properties ◽  
Dft Calculations ◽  
Phase Diagrams ◽  
Thermodynamic Stability ◽  
Electronic Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Spin Polarized

Spin-polarized DFT calculations were used to investigate the atomic, electronic structures of LaCoO3and La1−xSrxCoO3surfaces. The thermodynamic stability of these surfaces was analyzed with phase diagrams. Influence of Sr-doping was also examined.

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