The Atomic and Electronic Structures of Grain Boundaries in Silicon-Carbide and Silicon

1990 ◽  
Vol 193 ◽  
Author(s):  
M. Kohyama ◽  
S. Kose ◽  
M. Kinoshita ◽  
R. Yamamoto
Keyword(s):  
Electronic Structure ◽  
Electronic Structures ◽  
Boundary Energy ◽  
Tight Binding ◽  
Atomic Model ◽  
Electrostatic Energy ◽  
Hrem Image ◽  
Self Consistent ◽  
First Time ◽  
Atomic And Electronic Structure

ABSTRACTThe atomic and electronic structure of the {122} Σ=9 grain boundary in cubic SiC has been calculated for the first time using the self-consistent tight-binding (SCTB) method. An atomic model consisting of zigzag arrangement of 5-membered and 7-membered rings similar to that in the same boundary in Si or Ge has been constructed from a HREM image, although Si-Si and C-C wrong bonds are repeated alternately at the interface in this model. We have also performed calculations of the same boundary in Si using the SCTB method for comparison, and have obtained the results similar to those previously obtained by other theoretical schemes. The calculated boundary energy in SiC has shown that the present atomic model can exist stably as compared with the two surfaces, and the calculated boundary electronic structure in SiC has no deep states in the gap as well as that in Si. However, it has been found that the the increase in the electrostatic energy caused by the wrong bonds is a large part of the present boundary energy in SiC differently from that in Si, and it has been shown that the wrong bonds introduce the wrong-bond localised states at the band edges and within the valence band.

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.

ON THE ELECTRONIC STRUCTURE OF CrO2: NEW EXPERIMENTS AND THEORY

1993 ◽  
Vol 07 (01n03) ◽  
pp. 345-348 ◽  
Author(s):  
H. BRÄNDLE ◽  
D. WELLER ◽  
J. C. SCOTT ◽  
J. STICHT ◽  
P. M. OPPENEER ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Energy Range ◽  
Ab Initio ◽  
Optical Conductivity ◽  
Optical Constants ◽  
Conductivity Tensor ◽  
Experimental Confirmation ◽  
Spin Polarized ◽  
Self Consistent ◽  
First Time

Spectroscopic investigations of the optical constants n and k and the magneto-optical polar Kerr effects θK and εK were used to deterimine the diagonal and off-diagonal conductivity tensor elements of CrO 2 in the energy range 0.8-5eV. The data can be readily explained on the basis of self-consistent spin-polarized bandstructure calculations. A direct comparison of the measured and calculated diagonal optical conductivity is presented for the first time, which can be viewed as experimental confirmation of the ab initio calculated bandstructure of CrO 2.

Tight-binding-molecular-dynamics investigation of the atomic and electronic structure properties of a-C, a-Si and a-SiC

2003 ◽  
Vol 12 (3-7) ◽  
pp. 993-997 ◽  
Author(s):  
V.I. Ivashchenko ◽  
Patrice E.A. Turchi ◽  
V.I. Shevchenko ◽  
L.A. Ivashchenko ◽  
G.V. Rusakov
Keyword(s):  
Molecular Dynamics ◽  
Electronic Structure ◽  
Tight Binding ◽  
Atomic And Electronic Structure ◽  
Structure Properties

Tight-Binding Calculations of Complex Defects in Semiconductors: Comparison with AB Initio Results

1997 ◽  
Vol 491 ◽  
Author(s):  
M. Kohyama ◽  
N. Arai ◽  
S. Takeda
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Tight Binding ◽  
The Self ◽  
Planar Defects ◽  
Self Consistent ◽  
Tight Binding Method ◽  
Tilt Boundaries ◽  
Defects In Semiconductors

ABSTRACTComplex defects in Si and SiC such as coincidence tilt boundaries, planar defects and self-interstitial clusters were dealt with by using the transferable tight-binding method for Si and the self-consistent tight-binding method for SiC. These results have been compared with ab initio calculations of similar configurations. Essential features of the tight-binding results have been supported by the ab initio results. Especially, the agreement on stable atomic configurations is good, although there exits a tendency that energy increases are somewhat overestimated by the tight-binding methods. Serious faults have been found for the electronic structure by the tight-binding method for SiC.

NON-COLLINEAR MAGNETISM IN THE Fe3 MICROCLUSTER: FREE-STANDING VS SUPPORTED ENVIRONMENTS

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2532-2537
Author(s):  
E. MARTÍNEZ ◽  
R. ROBLES ◽  
A. VEGA ◽  
R. C. LONGO ◽  
L. J. GALLEGO
Keyword(s):  
Molecular Dynamics ◽  
Magnetic Properties ◽  
Electronic Structure ◽  
Tight Binding ◽  
Geometrical Configuration ◽  
Free Standing ◽  
Embedded Atom ◽  
Self Consistent ◽  
Tight Binding Method ◽  
Dynamics Simulations

The possibility of a non-collinear magnetic configuration of the Fe 3 microcluster supported on the Ni (001) surface has been investigated. The morphology of the supported cluster has been calculated by means of the modified embedded atom model with quenched molecular dynamics simulations, and the electronic structure for the most stable geometrical configuration has been studied using a self-consistent non-collinear spd tight-binding method parameterised to ab-initio tight-binding linear muffin tin orbital results. Our predictions are compared with previous results for the free-standing Fe 3 microcluster. The influence of the substrate in both the structure and the magnetic properties, particularly the onset of non-collinear magnetism, is discussed in detail.

Self-Consistent Tight-Binding Approximation Including Polarisable Ions

1997 ◽  
Vol 491 ◽  
Author(s):  
M. W. Finnis ◽  
A. T. Paxton ◽  
M. Methfesselt ◽  
M van Schilfgaarde
Keyword(s):  
Tight Binding ◽  
Structure Constant ◽  
Ceramic Materials ◽  
Fluorite Phase ◽  
Multipole Moments ◽  
Binding Model ◽  
Tight Binding Approximation ◽  
New Formalism ◽  
Self Consistent ◽  
First Time

ABSTRACTUntil recently, tight-binding has been applied to either covalent or metallic solid state systems, or charge transfer treated in a simple point charge framework. We present a self-consistent tight-binding model which, for the first time, includes electrostatic ion polar-isabihty and crystal field splitting. The tight-binding eigenvectors are used to construct multipole moments of the ionic charges which are used to obtain angular momentum components of the electrostatic potential in structure constant expansions. Our first test of the model is to study the phase stability in zirconia; in particular the instability of the fluorite phase to a spontaneous symmetry breaking, and its interpretation in terms of band effects and ion polarisability. This new formalism opens up the way to apply the tight-binding approximation to problems in which polarisation of atomic charges is important, for example oxides and other ceramic materials and surfaces of metals.

scholarly journals The electronic structure of quasi-free-standing germanene on monolayer MX (M = Ga, In; X = S, Se, Te)

2015 ◽  
Vol 17 (29) ◽  
pp. 19039-19044 ◽  
Author(s):  
Zeyuan Ni ◽  
Emi Minamitani ◽  
Yasunobu Ando ◽  
Satoshi Watanabe
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Ab Initio ◽  
Electronic Structures ◽  
Density Functional ◽  
Free Standing ◽  
Functional Theory ◽  
The Stability ◽  
First Time

For the first time by using the ab initio density functional theory, the stability and electronic structures of germanene on monolayer GaS, GaSe, GaTe and InSe have been investigated.

Sign in / Sign up

Export Citation Format

Share Document