scholarly journals Comparative Analysis of DFTU, ACBN0, and Hybrid Functionals on the Spin Density of YTiO3 and SrRuO3+

2021 ◽  
Vol 11 (2) ◽  
pp. 616
Author(s):  
Francesca Menescardi ◽  
Davide Ceresoli
Keyword(s):  
Density Functional Theory ◽  
Quantum Theory ◽  
Spin Density ◽  
Density Functional ◽  
Functional Theory ◽  
Atomic Orbitals ◽  
Hubbard U ◽  
Density Map ◽  
Hybrid Functionals ◽  
Standard Density

We present a quantitative analysis of the theoretical spin density map of two ferromagnetic perovskites, YTiO3 and SrRuO3. We calculated the spin density using the standard density functional theory (DFT)+U method, where the Hubbard U correction is applied to the Ti and Ru ions, and with the pseudo-hybrid ACBN0 method, where the Hubbard U parameters are determined self-consistently. The ACBN0 calculations yielded a large value of the Hubbard U of the oxygen 2p orbitals. We also used the screened hybrid HSE06 functional, which is widely used to describe the electronic structure of oxides. We used the Quantum Theory of Atoms in Molecules (QTAIM) theory and integrated the spin density in the atomic basins instead of projecting on atomic orbitals. This way, our results can be compared to experimental reports as well as to other DFT calculations.

scholarly journals Effects of the Hubbard U correction on the electronic and magnetic properties of the tetragonal V2P2 sheet

RSC Advances ◽  
2021 ◽  
Vol 11 (56) ◽  
pp. 35061-35068
Author(s):  
Yusuf Zuntu Abdullahi ◽  
Sohail Ahmad ◽  
Abdullahi Abdu Ibrahim
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Orthorhombic Phase ◽  
Theoretical Work ◽  
Basis Set ◽  
Functional Theory ◽  
Half Metallic ◽  
Atomic Orbitals ◽  
Recent Theoretical Work ◽  
Hubbard U

A recent theoretical work predicted the orthorhombic phase of the V2P2 sheet with the half-metallic electronic property using a linear combination of atomic orbitals (LCAO) basis set based on density functional theory (DFT).

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.

A complete ab initio thermodynamic and kinetic catalogue of the defect chemistry of hematite α-Fe2O3, its cation diffusion, and sample donor dopants

2021 ◽  
Author(s):  
Shehab Shousha ◽  
Sarah Khalil ◽  
Mostafa Youssef
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Defect Formation ◽  
Defect Chemistry ◽  
Cation Diffusion ◽  
Functional Theory ◽  
Migration Barriers ◽  
Hubbard U ◽  
And Migration ◽  
Formation Energies

This paper studies comprehensively the defect chemistry and cation diffusion in α-Fe2O3. Defect formation energies and migration barriers are calculated using density functional theory with a theoretically calibrated Hubbard U...

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