scholarly journals FINITE SIZE SCALING OF THE TYPICAL DENSITY OF STATES OF DISORDERED SYSTEMS WITHIN THE KERNEL POLYNOMIAL METHOD

2012 ◽  
Vol 11 ◽  
pp. 108-113 ◽  
Author(s):  
DANIEL JUNG ◽  
GERD CZYCHOLL ◽  
STEFAN KETTEMANN
Keyword(s):  
Density Of States ◽  
Disordered Systems ◽  
Local Density ◽  
Tight Binding ◽  
Finite Size ◽  
Mean Value ◽  
Polynomial Method ◽  
Anderson Transition ◽  
Geometrical Mean ◽  
Kernel Polynomial Method

We study the (Anderson) metal-insulator transition (MIT) in tight binding models (TBM) of disordered systems using the scaling behavior of the typical density of states (GDOS) as localization criterion. The GDOS is obtained as the geometrical mean value of the local density of states (LDOS) averaged over many different lattice sites and disorder realizations. The LDOS can efficiently be obtained within the kernel polynomial method (KPM). To check the validity and accuracy of the method, we apply it here to the standard Anderson model of disordered systems, for which the results (for instance for the critical disorder strength of the Anderson transition) are well known from other methods.

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.

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.

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.

ELECTRONIC LOCAL DENSITY OF STATES FOR THE TiNi(001) SURFACE

1999 ◽  
Vol 06 (05) ◽  
pp. 719-723 ◽  
Author(s):  
G. CANTO ◽  
R. DE COSS ◽  
D. A. PAPACONSTANTOPOULOS
Keyword(s):  
Surface Layer ◽  
Density Of States ◽  
Local Density ◽  
Tight Binding ◽  
First Principles Calculations ◽  
Local Density Of States ◽  
A Value ◽  
Atomic Surface ◽  
Surface Green Function ◽  
B2 Structure

We present a self-consistent tight-binding calculation of the electronic structure for the (001) surface of TiNi in the CsCl (B2) structure. The results were obtained using a three-center s–p–d orthogonal tight-binding Hamiltonian fitted to first-principles calculations, within the surface Green function matching formalism. We have analyzed the local density of states (LDOS) for cases with Ni or Ti at the surface layer. For the case where Ni is at the atomic surface layer we find that the corresponding LDOS consists predominantly of bonding states, like in the bulk but with a value at EF reduced by 38% with respect to the bulk; for this surface a strong peak in the LDOS was found at -1.4 eV below EF. For the case where Ti is at the atomic surface layer the corresponding LDOS consists mainly of antibonding states, but with a value at EF higher than in the bulk by 30%. Comparatively, the case where Ni is at the surface layer presents lower values of LDOS at EF and d holes with respect to the case where Ti is at the surface layer, and therefore more chemical activity can be expected for the Ti surface.

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