FIRST-PRINCIPLES CALCULATIONS ON ELECTRONIC STRUCTURES OF TiO2 ANATASE (101) SURFACES WITH N IMPURITIES

2011 ◽  
Vol 25 (02) ◽  
pp. 119-129 ◽  
Author(s):  
QI LI CHEN ◽  
GUANG ZHENG ◽  
KAI HUA HE ◽  
BO LI
Keyword(s):  
Band Gap ◽  
Electronic Structures ◽  
Density Functional ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Tio2 Anatase ◽  
Exchange Correlation ◽  
N Doping ◽  
Band Gap Narrowing ◽  
Coefficient Method

The electronic structures of nitrogen ( N )-doped TiO 2 anatase (101) surfaces have been investigated by density functional theory (DFT) plane-wave pseudopotential method with general gradient approximation (GGA) + U (Hubbard coefficient) method being adopted to describe the exchange-correlation effects. Both substitutional and interstitial N doping have been considered in this paper as well as the case of surface N adsorption. The results demonstrated that there is no obvious band gap narrowing observed by introducing N impurities except several N 2p states lying in the gap, whereas the introduction of oxygen vacancy was confirmed playing an important role on band gap narrowing. The results accord well with some experimental results.

First-Principles Calculations on Pure and Ga-Doped Anatase TiO2

2010 ◽  
Vol 156-157 ◽  
pp. 1385-1388
Author(s):  
Rui Qing Xu ◽  
Lan Fang Yao ◽  
Lin Li ◽  
Shuo Wang ◽  
Lin Lin Tian ◽  
...  
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Correlation Energy ◽  
Anatase Tio2 ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Band Gap Narrowing

First-principles calculations using the plane-wave pseudo-potential (PWPP) method based on the density functional theory (DFT) is employed to study the crystal structure, band gap, density of states of anatase TiO2 doped with gadolinium (Gd). The generalized gradient approximation (GGA) based on exchange-correlation energy optimization is employed to calculate them. The calculated results demonstrate that the mixing of gadolinium dopants induces states with original titanium 3d and oxygen 2p valence band attributes to the band gap narrowing. This can enhance the photocatalytic activity of anatase TiO2.

Indirect-Direct Band Gap Transition by Van Der Waals Interaction Engineering in MoS2/WS2 Bilayer Heterojunction

2014 ◽  
Vol 614 ◽  
pp. 70-74 ◽  
Author(s):  
Hai Ning Cao ◽  
Zhi Ya Zhang ◽  
Ming Su Si ◽  
Feng Zhang ◽  
Yu Hua Wang
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Direct Band Gap ◽  
The Density Functional Theory ◽  
Direct Band ◽  
Electric Filed

First principles calculations based on the density functional theory (DFT) are employed to estimate the electronic structures of bilayer heterostructure of MoS2/WS2. The dependences of the band structures on external electric field and interlayer separation are evaluated. The external electric filed induces a semiconductor-metal transition. At the same time, a larger interlayer separation, corresponding to a weaker interlayer interaction, makes an indirect-direct band gap transition happen for the heterojunction. Our results demonstrate that electronic structure tailoring of two-dimensional layered materials should include both spatial symmetry control and interlayer vdW interactions engineering.

First-Principles Calculations on Pure and Y-Doped Anatase TiO2

2013 ◽  
Vol 562-565 ◽  
pp. 1166-1170 ◽  
Author(s):  
Xiong Tang ◽  
Lan Fang Yao ◽  
Xin Pei Yan ◽  
Jun Long Kang
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Correlation Energy ◽  
Partial Density ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Calculation Results ◽  
Band Gap Narrowing

Using the First principles calculations, the crystal structure, band gap, total and partial density of states (DOS) of anatase TiO2and anatase TiO2doped with Yttrium were calculated by a plane-wave pseudopotential (PWPP) method based on density functional theory (DFT). The generalized gradient approximation (GGA) based on exchange-correlation energy optimization was employed to calculate them. From the calculation results, the band gap of anatase TiO2and Y3+doped TiO2are about 2.15eV and 0.86eV. The calculated results demonstrated that the mixing of Yttrium (Y) dopants induces states with original titanium 3d and oxygen 2p valence band attributes to the band gap narrowing. This can enhance the photocatalytic activity of anatase TiO2.

scholarly journals Electronic Structures of S/C-Doped TiO2Anatase (101) Surface: First-Principles Calculations

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Qili Chen ◽  
Min Liu ◽  
Kaihua He ◽  
Bo Li
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Chemical Potential ◽  
Synergistic Effects ◽  
Functional Theory ◽  
Calculated Density ◽  
Cation Doping ◽  
C Doping ◽  
Band Gap Narrowing ◽  
Coefficient Method

The electronic structures of sulfur (S) or carbon (C)-doped TiO2anatase (101) surfaces have been investigated by density functional theory (DFT) plane-wave pseudopotential method. The general gradient approximation (GGA) +U(Hubbard coefficient) method has been adopted to describe the exchange-correlation effects. All the possible doping situations, including S/C dopants at lattice oxygen (O) sites (anion doping), S/C dopants at titanium (Ti) sites (cation doping), and the coexisting of anion and cation doping, were studied. By comparing the formation energies, it was found that the complex of anion and cation doping configuration forms easily in the most range of O chemical potential for both S and C doping. The calculated density of states for various S/C doping systems shows that the synergistic effects of S impurities at lattice O and Ti sites lead a sharp band gap narrowing of 1.35 eV for S-doped system comparing with the pure TiO2system.

Synergistic effects on band gap-narrowing in titania by doping from first-principles calculations: density functional theory studies

2011 ◽  
Vol 1352 ◽  
Author(s):  
Run Long ◽  
Niall J. English
Keyword(s):  
Visible Light ◽  
Band Gap ◽  
Density Functional ◽  
Synergistic Effects ◽  
Theoretical Calculations ◽  
Binding Energies ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Band Gap Narrowing ◽  
Formation Energies

ABSTRACTThe large intrinsic band gap in TiO2 has hindered severely its potential application for visible-light irradiation. We have used a passivated approach to modify the band edges of anatase-TiO2 by codoping of X (N, C) with transition metals (TM=W, Re, Os) to extend the absorption edge to longer visible-light wavelengths. It was found that all the codoped systems can narrow the band gap significantly; in particular, (N+W)-codoped systems could serve as remarkably better photocatalysts with both narrowing of the band gap and relatively smaller formation energies and larger binding energies than those of (C+TM) and (N+TM)-codoped systems. Our theoretical calculations help to rationalise experimental results and provide reasonably meaningful guides for experiment to develop more powerful visible-light photocatalysts.

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.

Electronic structure of cubic BaTbO3 from first-principles pseudopotential calculations

2006 ◽  
Vol 84 (2) ◽  
pp. 115-120 ◽  
Author(s):  
G Y Gao ◽  
K L Yao ◽  
Z L Liu
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Pseudopotential Calculations ◽  
Correlation Potential ◽  
Density Contour

First-principles calculations of the electronic structure are performed for cubic BaTbO3 using the plane-wave pseudopotential method within the framework of density functional theory and using the generalized gradient approximation for the exchange-correlation potential. Our calculations show that cubic BaTbO3 is metallic, and that this metallic character is mainly governed by the Tb 4f electrons and the hybridization between the Tb 5d and O 2p states. From the analysis of the density of states, band structure, and charge density contour, we find that the chemical bonding between Tb and O is covalent while that between Ba and TbO3 is ionic. PACS Nos.: 71.15.Mb, 71.20.-b

scholarly journals First principles calculations on theoretical band gap improvement of IIIA-VA zinc-blende semiconductor InAs

2020 ◽  
Vol 31 (12) ◽  
pp. 2050178
Author(s):  
Waqas Mahmood ◽  
Arfan Bukhtiar ◽  
Muhammad Haroon ◽  
Bing Dong
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Local Density ◽  
Lattice Parameter ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Zinc Blende ◽  
Valence States ◽  
Direct Band ◽  
Experimental Findings

The structural, electronic, dielectric and vibrational properties of zinc-blende (ZB) InAs were studied within the framework of density functional theory (DFT) by employing local density approximation and norm-conserving pseudopotentials. The optimal lattice parameter, direct band gap, static dielectric constant, phonon frequencies and Born effective charges calculated by treating In-4d electrons as valence states are in satisfactory agreement with other reported theoretical and experimental findings. The calculated band gap is reasonably accurate and improved in comparison to other findings. This work will be useful for more computational studies related to semiconductor devices.

Density Functional Calculations on Electronic and Magnetic Properties of Fe-Pt Systems

2005 ◽  
Vol 475-479 ◽  
pp. 3103-3106 ◽  
Author(s):  
You Song Gu ◽  
Jian He ◽  
Zhen Ji ◽  
Xiao Yan Zhan ◽  
Yue Zhang ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Moment ◽  
Electronic Structures ◽  
Density Functional ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Generalized Gradient Approximation ◽  
Experimental Values ◽  
Pseudo Potential

The electronic structures and magnetic properties of Fe-Pt systems were calculated by CASTEP codes, which employed density functional theory, generalized gradient approximation (GGA), Perdew Burke Ernzerh exchange correlation, Pulay density-mixing scheme and Ultra Soft pseudo potential. The band structures and density of states (DOS) were calculated, together with band populations and magnetic properties. The calculated results of α-Fe show the validatiy of this method in predication magnetic properties. It is found that as the Pt concentration increases, Fe 4s and 3d electrons decrease while 4p electrons increase, and the magnetic moment of Fe atom increases. Pt atoms also contribute to the magnetic moment due to polarization. The calculated magnetization agrees with experimental values quite well.

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