scholarly journals Oxygenation mediating the valence density-of-states and work function of Ti(0001) skin

2015 ◽  
Vol 17 (15) ◽  
pp. 9867-9872 ◽  
Author(s):  
Lei Li ◽  
Fanling Meng ◽  
Hongwei Tian ◽  
Xiaoying Hu ◽  
Weitao Zheng ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Work Function ◽  
Valence Band ◽  
Density Of States ◽  
Density Functional ◽  
Lone Pair ◽  
Oxygen Adsorption ◽  
Band Edge ◽  
Valence Band Edge ◽  
Functional Theory

We report density functional theory observations that confirm the presence of predicted DOS features of holes and nonbonding lone pair DOS near the valence band edge of oxygen adsorption on the Ti(0001) surface.

A STUDY ON STRAIN AFFECTING ELECTRONIC STRUCTURE OF WURTZITE ZnO BY FIRST PRINCIPLES

2009 ◽  
Vol 23 (19) ◽  
pp. 2339-2352 ◽  
Author(s):  
LI BIN SHI ◽  
SHUANG CHENG ◽  
RONG BING LI ◽  
LI KANG ◽  
JIAN WEI JIN ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Band Structure ◽  
Valence Band ◽  
Density Of States ◽  
First Principles ◽  
Density Functional ◽  
Functional Theory ◽  
Electron Density Difference ◽  
Different Strains

Density of states and band structure of wurtzite ZnO are calculated by the CASTEP program based on density functional theory and plane-wave pseudopotential method. The calculations are carried out in axial and unaxial strains, respectively. The results of density of states in different strains show that the bottom of the conduction band is always dominated by Zn 4s, and the top of valence band is always dominated by O 2p. The variation of the band gap calculated from band structure is also discussed. In addition, p-d repulsion is used in investigating the variation of the top of the valence band in different strains and the results can be verified by electron density difference.

scholarly journals Defects in SiC for Quantum Computing

MRS Advances ◽  
2019 ◽  
Vol 4 (40) ◽  
pp. 2217-2222
Author(s):  
Renu Choudhary ◽  
Rana Biswas ◽  
Bicai Pan ◽  
Durga Paudyal
Keyword(s):  
Band Gap ◽  
Valence Band ◽  
Density Functional ◽  
Single Photon ◽  
Band Edge ◽  
Valence Band Edge ◽  
Dangling Bonds ◽  
Defect Levels ◽  
Formation Energies ◽  
Qubit Operation

AbstractMany novel materials are being actively considered for quantum information science and for realizing high-performance qubit operation at room temperature. It is known that deep defects in wide-band gap semiconductors can have spin states and long coherence times suitable for qubit operation. We theoretically investigate from ab-initio density functional theory (DFT) that the defect states in the hexagonal silicon carbide (4H-SiC) are potential qubit materials. The DFT supercell calculations were performed with the local-orbital and pseudopotential methods including hybrid exchange-correlation functionals. Di-vacancies in SiC supercells yielded defect levels in the gap consisting of closely spaced doublet just above the valence band edge, and higher levels in the band gap. The divacancy with a spin state of 1 is charge neutral. The divacancy is characterized by C-dangling bonds and a Si-dangling bonds. Jahn-teller distortions and formation energies as a function of the Fermi level and single photon interactions with these defect levels will be discussed. In contrast, the anti-site defects where C, Si are interchanged have high formation energies of 5.4 eV and have just a single shallow defect level close to the valence band edge, with no spin. We will compare results including the defect levels from both the electronic structure approaches.

Na2M2(SO4)3 (M = Fe, Mn, Co and Ni): towards high-voltage sodium battery applications

2016 ◽  
Vol 18 (14) ◽  
pp. 9658-9665 ◽  
Author(s):  
Rafael B. Araujo ◽  
Sudip Chakraborty ◽  
Prabeer Barpanda ◽  
Rajeev Ahuja
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Charge Transfer ◽  
Redox Potential ◽  
Density Of States ◽  
High Voltage ◽  
Density Functional ◽  
Structure Evolution ◽  
Sodium Ions ◽  
Functional Theory

We have employed density functional theory to systematically investigate the crystal structure evolution, density of states and charge transfer with sodium ions insertion, and the corresponding average redox potential, for Na2M2(SO4)3 (M = Fe, Mn, Co and Ni).

scholarly journals Unexpectedly Large Couplings Between Orthogonal Units in Anthraquinone Polymers

2019 ◽  
Author(s):  
Rocco Peter Fornari ◽  
Piotr de Silva
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Lone Pair ◽  
Localized States ◽  
Ab Initio Molecular Dynamics ◽  
Coupling Mechanism ◽  
Functional Theory ◽  
Pi Interactions

Directly linked polyanthraquinones have relatively large electronic couplings between charge-localized states despite near-orthogonality of the monomer units. By using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations, we investigate this unusual coupling mechanism and show that this is due to strong lone pair-pi interactions, which are maximized around orthogonal conformations. We find that such materials are largely resilient to dynamic disorder and are promising for organic electronics applications.

scholarly journals Pt Cluster Modified h-BN for Gas Sensing and Adsorption of Dissolved Gases in Transformer Oil: A Density Functional Theory Study

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1746 ◽  
Author(s):  
Yingang Gui ◽  
Tao Li ◽  
Xin He ◽  
Zhuyu Ding ◽  
Pingan Yang
Keyword(s):  
Density Functional Theory ◽  
Density Of States ◽  
Density Functional ◽  
Hexagonal Boron Nitride ◽  
Energy Charge ◽  
Boron Nitride Nanotubes ◽  
Transformer Oil ◽  
Total Density ◽  
Functional Theory ◽  
Pt Cluster

Hexagonal-Boron nitride nanotubes (h-BN) decorated with transition metals have been widely studied due to their enhanced physicochemical properties. In this paper, Pt cluster-modified h-BN is proposed as a sensitive material for a novel gas sensor for the online malfunction monitoring of oil-immersed transformers. The inner oil is ultimately decomposed to various gases during the long-term use of oil-immersed transformers. Exposure to excessively high temperatures produces the alkanes CH4 and C2H6, whereas different degrees of discharge generate H2 and C2H2. Therefore, the identification of H2, CH4, and C2H2 gas efficiently measures the quality of transformers. Based on the density functional theory, the most stable h-BN doped with 1–4 Pt atoms is employed to simulate its adsorption performance and response behavior to these typical gases. The adsorption energy, charge transfer, total density of states, projected density of states, and orbital theory of these adsorption systems are analyzed and the results show high consistency. The adsorption ability for these decomposition components are ordered as follows: C2H2 > H2 > CH4. Pt cluster-modified h-BN shows good sensitivity to C2H2, H2, with decreasing conductivity in each system, but is insensitive to CH4 due to its weak physical sorption. The conductivity change of Ptn-h-BN is considerably larger upon H2 than that upon C2H2, but is negligible upon CH4. Our calculations suggest that Pt cluster modified h-BN can be employed in transformers to estimate their operation status.

scholarly journals Theoretical design of a technetium-like alloy and its catalytic properties

2019 ◽  
Vol 10 (21) ◽  
pp. 5461-5469
Author(s):  
Wei Xie ◽  
Michihisa Koyama
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Catalytic Activity ◽  
Density Of States ◽  
Phase Stability ◽  
Density Functional ◽  
Catalytic Properties ◽  
Functional Theory ◽  
Theoretical Design ◽  
Structure Phase

Based on the concept of density of states (DOS) engineering, we theoretically designed a pseudo-Tc material (Mo–Ru alloy) and investigated its electronic structure, phase stability and catalytic activity by using density functional theory.

XPS, AES AND UPS INVESTIGATION OF SnO2/Si AND DFT-BASED THEORETICAL STUDY WITHIN THE mBJ-GGA SCHEME

2020 ◽  
pp. 2050048
Author(s):  
A. MOKADEM ◽  
M. BOUSLAMA ◽  
B. KHAROUBI ◽  
A. OUERDANE ◽  
R. KHENATA ◽  
...  
Keyword(s):  
Valence Band ◽  
Density Of States ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Electronic Distribution ◽  
Complementary Techniques ◽  
Uv Photoelectron Spectroscopy ◽  
Theoretical Results

We investigate the growth performance of tin oxide on the Si substrate, achieved by spray pyrolysis using the sensitive analysis techniques X-Ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). These complementary techniques confirm the growth of homogeneous SnO2 thin films. We also study the electronic distribution of the valence band of SnO2 theoretically using density functional theory (DFT). The chemical and physical properties of the material depend on the electron structure varying as a function of energy. The density of states (DOS) is calculated using the modified Becke–Johnson-Generalized Gradient Approximation (mBJ-GGA) in order to identify the electronic orbitals and the importance of their contribution to the electronic structure of the valence band. Furthermore, we use the experimental technique UV Photoelectron Spectroscopy (UPS) for studying the electronic distribution within the valence band and for validating the theoretical results of the density of states of SnO2/Si.

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