scholarly journals ELECTRONIC STATES AND LOCAL DENSITY OF STATES NEAR GRAPHENE CORNER EDGE

2012 ◽  
Vol 11 ◽  
pp. 151-156 ◽  
Author(s):  
YUJI SHIMOMURA ◽  
YOSITAKE TAKANE ◽  
KATSUNORI WAKABAYASHI
Keyword(s):  
Density Of States ◽  
Nearest Neighbor ◽  
Local Density ◽  
Tight Binding ◽  
Localized States ◽  
Destructive Interference ◽  
Edge States ◽  
Local Density Of States ◽  
Binding Model ◽  
Recursion Method

We study that stability of edge localized states in semi-infinite graphene with a corner edge of the angles 60°, 90°, 120° and 150°. We adopt a nearest-neighbor tight-binding model to calculate the local density of states (LDOS) near each corner edge using Haydock's recursion method. The results of the LDOS indicate that the edge localized states stably exist near the 60°, 90°, and 150° corner, but locally disappear near the 120° corner. By constructing wave functions for a graphene ribbon with three 120° corners, we show that the local disappearance of the LDOS is caused by destructive interference of edge states and evanescent waves.

ENERGY GAP DEPENDENCE ON ANION CONCENTRATION FOR GaxIn1-xAsyP1-y QUATERNARY ALLOY BY RECURSION METHOD

2004 ◽  
Vol 18 (18) ◽  
pp. 955-962
Author(s):  
MUSA EL-HASAN ◽  
REZEK ESTATIEH
Keyword(s):  
Density Of States ◽  
Energy Gap ◽  
Local Density ◽  
Tight Binding ◽  
Quaternary Alloy ◽  
Average Density ◽  
Local Density Of States ◽  
Recursion Method ◽  
Orbital Decomposition ◽  
Lattice Matched

Three terminators have been tested, square root terminator, quadreture terminator and linear terminator, it was found that the linear terminator is the best, so it was used in calculating local density of states (LDOS) and it's orbital decomposition, alloy average density of states, and energy gap for different anion concentrations for InP lattice matched alloy. The results were compared with our previous calculations of (LDOS), and results from other methods. Energy gap was compared with experimental measurements. A five orbital sp3s* per atom model was used in the tight-binding representation of the Hamiltonian.

Effects of band hybridization on electronic properties in tuning armchair graphene nanoribbons

2016 ◽  
Vol 94 (2) ◽  
pp. 218-225 ◽  
Author(s):  
M. Khatun ◽  
Z. Kan ◽  
A. Cancio ◽  
C. Nelson
Keyword(s):  
Fermi Level ◽  
Density Of States ◽  
Graphene Nanoribbons ◽  
Local Density ◽  
Tight Binding ◽  
Edge States ◽  
Local Density Of States ◽  
Periodic Patterns ◽  
Armchair Graphene Nanoribbons ◽  
Armchair Graphene

We explore a model of armchair graphene nanoribbons tuned by functionalizing the edge states. Edge modifications are modeled by changing the electronic energy of the edge states in specific periodic patterns. The model can be considered to mimic a controlled doping process with different elements. The band structure, density of states, conductance, and local density of states are calculated, using the tight binding approach, Green’s function methodology, and the Landauer formula. The results show interesting behaviors, which are considerably different from the properties of the perfect nanoribbons. The hybridization of conducting bands with non-conducting bands, which appear perfectly flat in the perfect ribbon, opens up and modifies gaps in conductance near the Fermi level. One particular pattern of edge functionalization causes a strong, symmetric, and systematic band gap change about the Fermi level, modifying the electronic characteristics in the energy dispersion, density of states, local density of states, and conductance.

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.

Calculation of bulk and surface electronic properties of diamond-like semiconductors

1984 ◽  
Vol 49 (3) ◽  
pp. 666-672 ◽  
Author(s):  
G. V. Gadiyak ◽  
A.A. Karpushin ◽  
Yu. N. Morokov ◽  
Mojmír Tomášek
Keyword(s):  
Experimental Data ◽  
Chemical Nature ◽  
Crystal Surface ◽  
Local Density ◽  
Surface States ◽  
Localized States ◽  
Total Density ◽  
Local Density Of States ◽  
Recursion Method ◽  
The Ideal

Local density of states (LDS) calculations have been performed by the recursion method for a model diamond-like semiconductor. LDS have been obtained for the following situations: the bulk, the vacancy and bivacancy in the bulk, the ideal (100) and (111) surfaces and the steps on these surfaces. Numerical results have been compared with experimental data for silicon. The calculated LDS show a one to one correspondence between the number of broken bonds on the investigated atom and the type of localized states near that atom. This supports the idea about the chemical nature of surface states, since the presence of steps on a strictly oriented surface leads to the appearance in the total density of surface states of additional peaks corresponding to another crystal surface.

A Cluster Calculation of B and P Impurities in Amorphous Silicon

1990 ◽  
Vol 209 ◽  
Author(s):  
L. Enrique Sansores ◽  
R.M. Valladares ◽  
J.A. Cogordan ◽  
A.A. Valladares
Keyword(s):  
Solid State ◽  
Density Of States ◽  
Nearest Neighbor ◽  
Local Density ◽  
Cluster Calculation ◽  
Local Density Of States ◽  
Ionic Component ◽  
Pure Silicon ◽  
Hartree Fock ◽  
Covalent Nature

ABSTRACTThe local density of states and charge density contours of clusters of the type ISi20H28, where I can be Si, B or P, was calculated using the well-known pseudopotential SCF Hartree-Fock Method (and the HONDO Program). It is found that the covalent nature of the bonding in pure silicon gets altered and gives rise to an ionic component when B and P are substituted in the center of the cluster. Also, the local density of states in the neighborhood of a Si atom, nearest neighbor to the center of the cluster, show a splitting of the p-states at the top of the valence band in pure silicon when B is substituted, and a new p-state appears in the band gap when P is sustituted. These results are analyzed in the light of the local changes and its relevance to the solid state properties.

scholarly journals SURFACE EFFECTS ON THE STATISTICS OF THE LOCAL DENSITY OF STATES IN METALLIC NANOPARTICLES: MANIFESTATION ON THE NMR SPECTRA

2005 ◽  
Vol 19 (25) ◽  
pp. 1285-1294 ◽  
Author(s):  
JOSÉ A. GASCÓN ◽  
HORACIO M. PASTAWSKI
Keyword(s):  
Density Of States ◽  
Metallic Nanoparticles ◽  
Local Density ◽  
Scaling Law ◽  
Tight Binding ◽  
Surface States ◽  
Aluminum Nanoparticles ◽  
Binding Model ◽  
Electronic Density ◽  
Knight Shifts

In metallic nanoparticles, shifts in the ionization energy of surface atoms with respect to bulk atoms can lead to surface bands. Within a simple Tight Binding model we find that the projection of the electronic density of states on these sites presents two overlapping structures. One of them is characterized by the level spacing coming from bulk states and the other arises from the surface states. In very small particles, this effect contributes to an over-broadening of the NMR absorption spectra, determined by the Knight shift distribution of magnetic nuclei. We compare our calculated Knight shifts with experiments on aluminum nanoparticles, and show that the deviation of the scaling law as a function of temperature and particle size can be explained in terms of surface states.

Effect of the Local Disorder in a-Si on the Electronic Density of States at the Band Edges.

1991 ◽  
Vol 219 ◽  
Author(s):  
B. N. Davidson ◽  
G. Lucovsky ◽  
J. Bernholc
Keyword(s):  
Density Of States ◽  
Nearest Neighbor ◽  
Bond Angle ◽  
Local Density ◽  
Tight Binding ◽  
Bethe Lattice ◽  
Neighbor Interaction ◽  
Lattice Method ◽  
Electronic Density ◽  
Interaction Terms

ABSTRACTWe have systematically investigated the formation of electronic states in the region of the conduction and valence band edges of a Si as functions of variations in the bond angle distributions. Local Density of States (LDOS) for Si atoms in disordered environments have been calculated using the cluster Bethe lattice method with a tight-binding Hamiltonian containing both first and second nearest neighbor interaction terms. LDOS for atoms with bond angle dis ortions in the nearest neighbor and second neighbor shells are compared and contrasted, both showing an influence on the LDOS near the gap. We also consider the role of the second neighbor term in the Hamiltonian by comparing the DOS for a distoned infinite Bethe lattice using Hamiltonians with and without the second neighbor interactions. It is found that in this case the second neighbor interaction terms cause greater conduction band tailing than using the nearest neighbor interaction terms alone.

Calculations of the local density of states ofNiSi2, NiSi,Ni2Si, andNi3Si using the Haydock recursion method

1988 ◽  
Vol 38 (14) ◽  
pp. 9511-9516 ◽  
Author(s):  
Keith L. Peterson ◽  
J. S. Hsiao ◽  
D. R. Chopra ◽  
T. R. Dillingham
Keyword(s):  
Density Of States ◽  
Local Density ◽  
Local Density Of States ◽  
Recursion Method
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