Electronic Structures of β-SiC(001) Surfaces and Al/β-SiC(001) Interface

1994 ◽  
Vol 339 ◽  
Author(s):  
Xiao Hu ◽  
Hong Yan ◽  
Fumio S. Ohuchi
Keyword(s):  
Density Of States ◽  
Electronic Structures ◽  
Surface Density ◽  
Tight Binding ◽  
Bonded Interface ◽  
Surface Reconstructions ◽  
Tight Binding Method ◽  
Theoretical Results ◽  
Good Agreement ◽  
The Ideal

ABSTRACTSurface electronic structures of β-SiC reconstructed (001) surfaces and the Al/β-SiC(001) interface have been investigated by employing a tight-binding method. Distinct surface electronic characteristics corresponding to different surface reconstructions are discussed based on the interpretation of surface density of states. The calculations of the Al/β-SiC (001) interface indicate that aluminum deposition on β-SiC(001) surface may induce the substrate to return to the ideal unreconstructed surface and that Al-C interaction is stronger than Al-Si interaction. Al deposition on C-rich surfaces may form a better bonded interface than that on the Si-rich surfaces. Our findings are in good agreement with available experimental and theoretical results.

MAGNETIC SUSCEPTIBILITY OF YRh2

1993 ◽  
Vol 07 (01n03) ◽  
pp. 834-837
Author(s):  
H. YAMADA ◽  
W. STEINER
Keyword(s):  
Magnetic Susceptibility ◽  
Temperature Dependence ◽  
Density Of States ◽  
Phase Structure ◽  
Magnetic Measurements ◽  
Tight Binding ◽  
The Other ◽  
Spin Fluctuations ◽  
Tight Binding Method ◽  
Good Agreement

Magnetic measurements for YRh2 with the cubic Laves phase structure were performed between 4.2 and 600 K. It was observed that the susceptibility shows a very weak temperature dependence and our data are about 40 % larger than the observed one by Loebich and Raub. On the other hand, the temperature dependence of the susceptibility was also estimated theoretically, by using the density-of-states curve calculated in the tight-binding method and by taking into account the effect of spin fluctuations. A good agreement between our observed and calculated results is obtained.

Electronic band structure of silver low-index surfaces: a tight-binding study

2020 ◽  
Vol 98 (5) ◽  
pp. 488-496
Author(s):  
H.J. Herrera-Suárez ◽  
A. Rubio-Ponce ◽  
D. Olguín
Keyword(s):  
Band Structure ◽  
Density Of States ◽  
Electronic Band Structure ◽  
Local Density ◽  
Tight Binding ◽  
Theoretical Data ◽  
Binding Study ◽  
Local Density Of States ◽  
Electronic Band ◽  
Tight Binding Method

We studied the electronic band structure and corresponding local density of states of low-index fcc Ag surfaces (100), (110), and (111) by using the empirical tight-binding method in the framework of the Surface Green’s Function Matching formalism. The energy values for different surface and resonance states are reported and a comparison with the available experimental and theoretical data is also done.

Tight-Binding Study of the {211} Σ=3 Grain Boundary in Cubic Silicon-Carbide

1994 ◽  
Vol 339 ◽  
Author(s):  
M. Kohyama ◽  
R. Yamamoto
Keyword(s):  
Grain Boundaries ◽  
Electronic Structures ◽  
Tight Binding ◽  
The Self ◽  
Localized States ◽  
General Definition ◽  
Self Consistent ◽  
Tight Binding Method ◽  
Definition Of ◽  
Cubic Silicon Carbide

ABSTRACTIn grain boundaries in compound semiconductors such as SiC, the interface stoichiometry and the wrong bonds between like atoms are of much importance. Firstly, a general definition of the interface stoichiometry in such grain boundaries has been discussed. Secondly, the atomic and electronic structures of the {211} Σ=3 boundary in SiC have been examined by using the self-consistent tight-binding method, based on the atomic models with bonding networks similar to those in the models of the same boundary in Si or Ge. The wrong bonds have significant effects through the large electrostatic repulsion and the generation of localized states as well as those in the {122} Σ=9 boundary in SiC. And the different bond lengths of the wrong bonds very much affect the local bond distortions at the interfaces, which determines the relative stability among the present models.

First-Principle Study on the Structural Phase Transition, and Electronic Structures of Cobalt under Pressure

2015 ◽  
Vol 729 ◽  
pp. 15-20
Author(s):  
Hong Bo Zhu ◽  
Dun Qiang Tan ◽  
Zhi Huang Xiong
Keyword(s):  
Phase Transition ◽  
Electronic Structures ◽  
Density Functional ◽  
Structural Parameters ◽  
Structural Phase ◽  
First Principles Calculation ◽  
Functional Theory ◽  
Calculated Equilibrium ◽  
Theoretical Results ◽  
Good Agreement

The structural phase transitions and electronic structures of Co are investigated by using the first-principles calculation based on density-functional theory (DFT). Our calculated equilibrium structural parameters of Co are in good agreement with the available experimental data and other theoretical results. The calculated phase transition hcp-Co → fcc-Co at ca. 125.25 GPa. The magnetic moment of hcp-Co and fcc-Co drops to zero at 155 GPa and 77 GPa, respectively.

Efficient Photoluminescence from Thin Films of Polypyrrole

2010 ◽  
Vol 663-665 ◽  
pp. 300-303 ◽  
Author(s):  
Yuan Ming Huang ◽  
Bao Gai Zhai ◽  
Qing Lan Ma
Keyword(s):  
Thin Films ◽  
Valence Band ◽  
Electronic Structures ◽  
Conjugated Polymer ◽  
Tight Binding ◽  
Electronic Transitions ◽  
Visible Absorption ◽  
Ultraviolet Excitation ◽  
Tight Binding Method ◽  
Visible Absorption Spectroscopy

A soluble polypyrrole without any substituent groups was obtained by controlling the oxidation level of polypyrrole in the presence of oxygen. Upon the exposure to the 325 nm ultraviolet excitation from a helium-cadmium laser, thin films of the non-substituted polypyrrole could give off strong photoluminescence with its peak at about 530 nm. To elucidate the origin of the recorded strong photoluminescence, we measured the absorption spectra of the polypyrrole thin films with ultraviolet-visible absorption spectroscopy and our data indicated the appropriately oxidized polypyrrole are free of polarons. With the help of the electronic structures calculated with Hückel tight-binding method, the intense photoluminescence is interpreted in terms of the direct electronic transitions from the conduction band to valence band of the conjugated polymer.

Deep-Blue Photoluminescent Properties of a Liquid Crystal TB10A

2011 ◽  
Vol 181-182 ◽  
pp. 33-38 ◽  
Author(s):  
Qing Lan Ma ◽  
Rui Xiong ◽  
Yuan Ming Huang
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Electronic Structures ◽  
Room Temperature ◽  
Tight Binding ◽  
Electronic Structure Calculations ◽  
Scanning Calorimetry ◽  
Deep Blue ◽  
Tight Binding Method ◽  
Structure Calculations

A typical liquid crystal (LC) N,N-(terephthalylidene) bis (4-decylbenzenamine) (TB10A) was firstly synthesized at room temperature. The synthesized LC TB10A were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), ultraviolet-visible (UV-vis) spectrophotometry, photoluminecence (PL) spectroscopy and electronic structure calculations. Upon the 325 nm excitation, the dilute tetrahydrofuran solutions of TB10A could give off blue PL. With Hückel tight-binding method, the electronic structures of the TB10A were calculated. Our results demonstrated that the deep-blue PL observed at about 489 nm (2.54 eV) can be assigned to theπ* →ntransition for the TB10A.

Optical Properties and Electronic Structures of a Liquid Crystal TBO10A

2011 ◽  
Vol 181-182 ◽  
pp. 110-114
Author(s):  
Yuan Ming Huang ◽  
Qing Lan Ma ◽  
Bao Gai Zhai
Keyword(s):  
Liquid Crystal ◽  
Electronic Structures ◽  
Room Temperature ◽  
Tight Binding ◽  
Electronic Structure Calculations ◽  
Scanning Calorimetry ◽  
Absorption Bands ◽  
Rigid Core ◽  
Tight Binding Method ◽  
Structure Calculations

A liquid crystal (LC) N,N-(terephthalylidene) bis (4-octyloxyaniline) (TBO10A) was synthesized at room temperature. The LC TBO10A were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), ultraviolet-visible spectrophotometry, photoluminecence (PL) spectroscopy and electronic structure calculations. In tetrahydrofuran solutions, two optical absorption bands were recorded for TBO10A at about 298 and 379 nm, respectively. Under the 325 nm excitation, dilute tetrahydrofuran solutions of the TBO10A can give off weak blue PL. With Hückel tight-binding method, the electronic structures of the TBO10A were calculated. Our results demonstrated that two absorptions can be attributed to theπ→π* andn→π* transitions in the rigid core of the TBO10A while the PL observed at about 481 nm (2.58 eV) can be assigned to theπ* →ntransition.

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