Ab initio Study of the Hydrogen Molecule on ZnO Surfaces

2011 ◽  
Vol 1327 ◽  
Author(s):  
Po-Liang Liu ◽  
Yen-Ting Wu ◽  
Yu-Jin Siao
Keyword(s):  
First Principles ◽  
Active Sites ◽  
Density Functional ◽  
Ab Initio Study ◽  
Dissociative Chemisorption ◽  
Total Energy Density ◽  
Energy Density Functional ◽  
Chemical Potentials ◽  
Rich Condition ◽  
Surface Models

ABSTRACTWe conduct first-principles total-energy density functional calculations to study the interaction of H2 on ZnO surfaces. Four surface models of Zn-terminated (0001)-, O-terminated (0001)-, $(10{\bar 1}0)-$, and $(2{\bar 1}{\bar 1}0)-$oriented ZnO planes in the presence of H2 are evaluated. The relative stability of four different surface models is examined as a function of the chemical potentials of oxygen and hydrogen. We find that only surfaces of O-terminated (0001)-oriented ZnO models exhibit active sites for the dissociation of H2, which in turn enables the formation of water from dissociative chemisorption of 2H on the O-terminated ZnO(0001) surface. The surface energy of O-terminated ZnO(0001) surface in the presence of water was found to be negative under the O-rich and H-rich condition. The findings agree with the experimental observations that ZnO epitaxial layers are easily etched by hydrogen at typical growth temperatures.

The Studies of ScB2 (0001) Surfaces from the First-Principles

2014 ◽  
Vol 989-994 ◽  
pp. 688-693
Author(s):  
Hui Zhao ◽  
Qian Han
Keyword(s):  
Energy Density ◽  
Total Energy ◽  
Electronic Properties ◽  
First Principles ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Surface Structures ◽  
Charge Accumulation ◽  
Total Energy Density ◽  
Energy Density Functional

We conduct first-principles total-energy density functional calculations to study the ScB2 (0001) surfaces. The optimized surface structures and electronic properties are obtained. The results show that Sc-terminated surface is thermodynamically more favorable in most of range. The relaxations indicate that it is mainly localized within top three layers and it is less relaxation for Sc-terminated surface. The surface induced features in DOS disappear slowly for the B-terminated surface but vanish rapidly for the Sc-terminated surface. For the Sc-terminated surface, it shows strong metallic property. Simultaneously, both termination surfaces are found charge accumulation relative to the idea surface. Sc-B bonds are strengthened result in the outermost interface spacing are all contracted.

scholarly journals Intermediate Band Studies of Substitutional V2+, Cr2+, and Mn2+ Defects in ZnTe Alloys

2020 ◽  
Vol 10 (24) ◽  
pp. 8937
Author(s):  
Jen-Chuan Tung ◽  
Bang-Wun Lin ◽  
Po-Liang Liu
Keyword(s):  
Energy Density ◽  
Transition Metal ◽  
First Principles ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Emission Spectra ◽  
Total Energy Density ◽  
Energy Density Functional ◽  
Intermediate Band ◽  
Jahn Teller

We present first-principles total-energy density functional calculations to study the intermediate band states of substitutional V2+, Cr2+, and Mn2+ ions in ZnTe alloys. The intermediate band states of substitutional transition metal defects of TM2+xZn1−xTe (TM = V, Cr, Mn) alloys are examined as their atomic, structural, and electronic analysis. Our findings show that the scissor-corrected transitions due to Jahn-Teller effects lead to the wavelengths 2530 nm and 2695 nm in the emission spectra. Our findings agree with previously reported experimental results.

scholarly journals Adsorption of NO2 and H2S on ZnGa2O4(111) Thin Films: A First-Principles Density Functional Theory Study

2020 ◽  
Vol 10 (24) ◽  
pp. 8822
Author(s):  
Jen-Chuan Tung ◽  
Yi-Hung Chiang ◽  
Ding-Yuan Wang ◽  
Po-Liang Liu
Keyword(s):  
Work Function ◽  
First Principles ◽  
Density Functional ◽  
Total Energy Density ◽  
Energy Density Functional ◽  
Functional Theory ◽  
Function Change ◽  
Work Function Change ◽  
H2s Adsorption ◽  
Maximum Work

We performed first-principles total-energy density functional calculations to study the reactions of NO2 and H2S molecules on Ga–Zn–O-terminated ZnGa2O4(111) surfaces. The adsorption reaction and work functions of eight NO2 and H2S adsorption models were examined. The bonding of the nitrogen atom from a single NO2 molecule to the Ga atom of the Ga–Zn–O-terminated ZnGa2O4(111) surfaces exhibited a maximum work function change of +0.97 eV. The bond joining the sulfur atom from a single H2S molecule and the Ga atom of Ga–Zn–O-terminated ZnGa2O4(111) surfaces exhibited a maximum work function change of −1.66 eV. Both results concur with previously reported experimental observations for ZnGa2O4-based gas sensors.

First-Principle Studies on the Stability of AlN(0001)/NbB2(0001) Interface

2014 ◽  
Vol 1052 ◽  
pp. 18-23
Author(s):  
Hui Zhao ◽  
Kai Yuan Liu ◽  
Qian Han
Keyword(s):  
Density Functional Theory ◽  
Energy Density ◽  
Density Functional ◽  
Stable Configuration ◽  
Stable Model ◽  
First Principle ◽  
Total Energy Density ◽  
Energy Density Functional ◽  
Functional Theory ◽  
The Stability

The stability behaviour of AlN(0001)/NbB2(0001) interface was calculated by first-principle total-energy density functional theory. The calculation indicated that the stable NbB2(0001) surface is B terminated. We joined the AlN(0001) slab and the NbB2(0001) slab with different terminations together to construct all possible AlN(0001)/NbB2(0001) interface models, and calculated their interface energies to confirm the relatively stable model. We concluded that the structure with Al is on top of B in the interface AlN (0001)/NbB2(0001) is the most stable configuration.

First-principles study on codoping effect to enhance photocatalytic activity of anatase TiO2

2017 ◽  
Vol 31 (06) ◽  
pp. 1750036
Author(s):  
Yujie Bai ◽  
Qinfang Zhang ◽  
Fubao Zheng ◽  
Yun Yang ◽  
Qiangqiang Meng ◽  
...  
Keyword(s):  
Visible Light ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Energy Gap ◽  
Density Functional Theory Calculations ◽  
Band Edge ◽  
Electron Hole ◽  
Functional Theory ◽  
Rich Condition

Codopant is an effective approach to modify the bandgap and band edge positions of transition metal oxide. Here, the electronic structures as well as the optical properties of pristine, mono-doped (N/P/Sb) and codoped (Sb, N/P) anatase TiO2 have been systematically investigated based on density functional theory calculations. It is found that mono-doped TiO2 exhibits either unoccupied or partially occupied intermediate state within the energy gap, which promotes the recombination of electron-hole pairs. However, the presence of (Sb, N/P) codopant not only effectively reduces the width of bandgap by introducing delocalized occupied intermediate states, but also adjusts the band edge alignment to enhance the hydrogen evolution activity of TiO2. Moreover, the optical absorption spectrum for (Sb, N/P) codoped TiO2, which is favored under oxygen-rich condition, demonstrates the improvement of its visible light absorption. These findings will promote the potential application of (Sb, N/P) codoped TiO2 photocatalysis for water splitting under visible light irradiation.

Ab initio study of hydrogen chemisorption in nitrogen-doped carbon nanotubes

2016 ◽  
Vol 18 (36) ◽  
pp. 25663-25670 ◽  
Author(s):  
Julian David Correa ◽  
Elizabeth Florez ◽  
Miguel Eduardo Mora-Ramos
Keyword(s):  
Carbon Nanotubes ◽  
First Principles ◽  
Density Functional ◽  
Periodic Boundary ◽  
Periodic Boundary Conditions ◽  
Hydrogen Chemisorption ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Nitrogen Doped ◽  
Nitrogen Doped Carbon

The electronic structure of single walled nitrogen-doped carbon nanotubes is calculated by first principles using density functional theory within the supercell approach with periodic boundary conditions.

scholarly journals David Godfrey Pettifor. 9 March 1945—16 October 2017

2019 ◽  
Vol 66 ◽  
pp. 329-353
Author(s):  
Adrian P. Sutton ◽  
Ralf Drautz ◽  
Vaclav Vitek
Keyword(s):  
Density Functional ◽  
Materials Science ◽  
Density Functional Theory Calculations ◽  
Interatomic Potentials ◽  
Total Energy Density ◽  
Energy Density Functional ◽  
Rigorous Testing ◽  
Materials Modelling ◽  
The Status ◽  
Theoretical Physicist

David Pettifor was a theoretical physicist who changed the nature of materials science by raising the status of materials modelling to that of materials characterization and processing. He believed that the subject advanced through the development of simple models that withstood rigorous testing against experiments and the most accurate numerical computations. Having been a pioneer of total energy density functional theory calculations, he went on to derive analytic interatomic potentials for transition metals and nearly-free-electron metals and alloys from quantum mechanical principles. He is probably best known for the development of highly successful structure maps for binary and pseudo-binary alloys that were used by alloy developers in industry to create intermetallic alloys with improved properties. At Oxford he established the first materials modelling laboratory, bringing together physicists, chemists, materials scientists and engineers to model materials across length and time scales, which became a flagship laboratory for materials scientists world-wide.

scholarly journals The nature of active sites for carbon dioxide electroreduction over oxide-derived copper catalysts

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Dongfang Cheng ◽  
Zhi-Jian Zhao ◽  
Gong Zhang ◽  
Piaoping Yang ◽  
Lulu Li ◽  
...  
Keyword(s):  
Active Sites ◽  
Density Functional ◽  
Heterogeneous Catalysts ◽  
Density Functional Theory Calculations ◽  
Copper Catalysts ◽  
Functional Theory ◽  
Surface Models ◽  
Cu Catalysts ◽  
Intense Debate

AbstractThe active sites for CO2 electroreduction (CO2R) to multi-carbon (C2+) products over oxide-derived copper (OD-Cu) catalysts are under long-term intense debate. This paper describes the atomic structure motifs for product-specific active sites on OD-Cu catalysts in CO2R. Herein, we describe realistic OD-Cu surface models by simulating the oxide-derived process via the molecular dynamic simulation with neural network (NN) potential. After the analysis of over 150 surface sites through NN potential based high-throughput testing, coupled with density functional theory calculations, three square-like sites for C–C coupling are identified. Among them, Σ3 grain boundary like planar-square sites and convex-square sites are responsible for ethylene production while step-square sites, i.e. n(111) × (100), favor alcohols generation, due to the geometric effect for stabilizing acetaldehyde intermediates and destabilizing Cu–O interactions, which are quantitatively demonstrated by combined theoretical and experimental results. This finding provides fundamental insights into the origin of activity and selectivity over Cu-based catalysts and illustrates the value of our research framework in identifying active sites for complex heterogeneous catalysts.

Stable ferromagnetic state in Si-doped AlN with cation vacancies: Ab-initio study

2016 ◽  
Vol 05 (03) ◽  
pp. 1650017
Author(s):  
Sandhya Chintalapati ◽  
Yuan Ping Feng
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Magnetic Moments ◽  
Ferromagnetic State ◽  
First Principles Calculations ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Spin Polarized ◽  
Si Doped

The magnetic property of Si-doped AlN with Al-vacancy is studied using first principles calculations based on spin polarized density functional theory. The Si dopant alone does not introduce the magnetic moment in AlN. However, the doping of Si in AlN reduces the formation energy caused by Al-vacancy, and stabilizes the spin polarized state. The magnetic moments are mainly localized on N atoms surrounding the defect. The strong ferromagnetic state is obtained in AlN due to the combined role of Al-vacancy and Si-dopant.

An accurate total energy density functional

2007 ◽  
Vol 107 (15) ◽  
pp. 2995-3000 ◽  
Author(s):  
Baojing Zhou ◽  
Yan Alexander Wang
Keyword(s):  
Energy Density ◽  
Total Energy ◽  
Density Functional ◽  
Total Energy Density ◽  
Energy Density Functional
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