A comparative study on the LDA + U and hybrid functional methods on the description of the electronic structure of YTiO3 under high pressure

2009 ◽  
Vol 87 (10) ◽  
pp. 1374-1382 ◽  
Author(s):  
Z. Song ◽  
J. J. Yang ◽  
J. S. Tse
Keyword(s):  
Electronic Structures ◽  
Local Density ◽  
Band Gaps ◽  
Density Approximation ◽  
Hybrid Functional ◽  
Functional Methods ◽  
Mixing Parameters ◽  
Hubbard U ◽  
Hubbard Parameter ◽  
Pressure Analysis

The electronic structures of YTiO3 under pressure have been studied with LDA + U (local density approximation + Hubbard parameter) and hybrid functional methods. From matching the experimental band gaps, the Hubbard U and hybrid functional mixing parameters were determined. It is found that both parameters vary with the pressure. Analysis of the electronic structures indicates that the description of the chemical bonding is also dependent on the method of choice.

Relation of Phase Stability Boundary to the Fill-Up Bonding States In Ni3V,Co3V and Fe3V

1990 ◽  
Vol 213 ◽  
Author(s):  
W. Lin ◽  
Jian-Hua Xu ◽  
A.J. Freeman
Keyword(s):  
Structural Stability ◽  
Electronic Structures ◽  
Local Density ◽  
Stability Boundary ◽  
The Self ◽  
Orbital Method ◽  
Density Approximation ◽  
Cohesive Properties ◽  
Self Consistent ◽  
Electronic Concentration

ABSTRACTThe electronic structures and cohesive properties of the intermetallics Ni3V, Co3V, and Fe3V in the L12 structure have been studied using the self-consistent total energy linear muffin-tin orbital method based on the local density approximation. The simple rigid-band concept appears to be adequate to explain the structural stability of these compounds. Further,the structural stability of the pseudobinary compounds (Ni,Co,Fe)3V has been investigated based on the rigid-band scheme. The correlation between the electronic concentration and the crystal structure is shown to be related to the fill-up of the bonding states.

Mechanism of enhanced photocatalytic activities on tungsten trioxide doped with sulfur: Dopant-type effects

2016 ◽  
Vol 30 (27) ◽  
pp. 1650340 ◽  
Author(s):  
Dan Li ◽  
Wei-Qing Huang ◽  
Zhong Xie ◽  
Liang Xu ◽  
Yin-Cai Yang ◽  
...  
Keyword(s):  
Electronic Structures ◽  
Tungsten Trioxide ◽  
Density Functional ◽  
Vacancy Defect ◽  
Band Gaps ◽  
Vacancy Defects ◽  
Density Functional Methods ◽  
Functional Methods ◽  
Photocatalytic Activities ◽  
Different Types

The enhanced photocatalytic activity of tungsten trioxide (WO3) has been observed experimentally via doping with S element as different dopant types. Herein, a comparative study on the effect of different types of S dopant and native vacancy defects on the electronic structure and optical properties of WO3 is presented by using hybrid Heyd–Scuseria–Ernzerhof 2006 (HSE06) density functional methods. Six possible models (S[Formula: see text]–WO3, S[Formula: see text]–WO3, V[Formula: see text]–WO3, V[Formula: see text]–WO3, S[Formula: see text] + V[Formula: see text]–WO3 and S[Formula: see text] + V[Formula: see text]–WO3) based on WO3 are tentatively put forward. It is found that cationic S doping (the substitution of W by S) is more favorable than anionic S doping (replacing O with S), and both cases become easier to form as native vacancy defect is accompanied. The electronic structures of doped WO3 depend on the type of dopant: anionic S doping results into three isolated levels in the upper part of valence band, while cationic S doping only induces an effective band gap reduction, which is critical for efficient light-to-current conversion. Interestingly, the isolated states near gap of WO3 would appear as long as native vacancy defects exist. The introduced levels or reduced band gaps make the systems responsed to the visible light, even further to a range of 400–700 nm. These findings can rationalize the available experimental results and pave the way for developing WO3-based photocatalysts.

scholarly journals Electronic structure and optical properties of (BeTe)n/(ZnSe)m superlattices

2016 ◽  
Vol 34 (1) ◽  
pp. 115-125 ◽  
Author(s):  
M. Caid ◽  
H. Rached ◽  
D. Rached ◽  
R. Khenata ◽  
S. Bin Omran ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Electronic Structure ◽  
Ground State ◽  
Optical Constants ◽  
Local Density ◽  
Band Gaps ◽  
Full Potential ◽  
Density Approximation ◽  
Binary Compounds

AbstractThe structural, electronic and optical properties of (BeTe)n/(ZnSe)m superlattices have been computationally evaluated for different configurations with m = n and m≠n using the full-potential linear muffin-tin method. The exchange and correlation potentials are treated by the local density approximation (LDA). The ground state properties of (BeTe)n/(ZnSe)m binary compounds are determined and compared with the available data. It is found that the superlattice band gaps vary depending on the layers used. The optical constants, including the dielectric function ε(ω), the refractive index n(ω) and the refractivity R(ω), are calculated for radiation energies up to 35 eV.

Theoretical investigation of the magnetic ordering and the superconducting state in rare earth iron pnictides

2014 ◽  
Vol 03 (04) ◽  
pp. 1450020 ◽  
Author(s):  
S. Abbaoui ◽  
A. Zaoui ◽  
S. Kacimi ◽  
M. Djermouni ◽  
M. Bououdina
Keyword(s):  
Rare Earth ◽  
Density Functional ◽  
Local Density ◽  
Magnetic Ordering ◽  
Ferromagnetic State ◽  
Iron Pnictides ◽  
Density Approximation ◽  
Functional Theory ◽  
Fermi Surfaces ◽  
Hubbard U

The superconductivity and magnetic phenomena of the rare earth iron pnictides R FePO (R = La , Sm ) are analyzed using ab initio density functional theory in the local density approximation (LDA) with the on-site Hubbard U eff parameter (LDA + U). The results of the magnetic properties, band structures and Fermi surfaces of the recently synthesized tetragonal layered iron pnictides superconductor SmFePO are presented in comparison with the superconductor LaFePO . The anti-ferromagnetic state [ Sm : AFM, Fe AFM_stripe] is found to be the most stable than the other possible phases, which is in agreement with experiment. The effect of the Hubbard correction is investigated and is found to be a necessary requirement for the accurate description of both the electronic structure and the Fermi surfaces.

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