A Cluster Calculation of B and P Impurities in Amorphous Silicon

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.

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Calculations of the Electronic Structure of Vacancies in a-Si:H

MRS Proceedings ◽

10.1557/proc-291-349 ◽

1992 ◽

Vol 291 ◽

Author(s):

Ariel A. Valladares ◽

L. Enrique Sansores

Keyword(s):

Electronic Structure ◽

Charge Density ◽

Density Of States ◽

Energy Gap ◽

Local Density ◽

Amorphous Solids ◽

Local Density Of States ◽

Hydrogen Atoms ◽

Hartree Fock ◽

Cluster Calculations

ABSTRACTThe electronic structure of random clusters has been used in the literature as representative of the electronic structure of random solids. In this work a calculation of the local density of states (LDOS) and charge density contours for clusters of the type XSi20H28 with X an Si atom, a vacancy or 4 hydrogen atoms, has been carried out. The method used was a pseudopotential SCF Hartree-Fock and the HONDO program. It is found that the generation of a vacancy in the center of the cluster (removal of the central Si atom), introduces p-like states in the energy gap of the LDOS for the region near the center of the cluster. The saturation of the dangling bonds of the vacancy with 4 hydrogen atoms removes the states within the gap. These results are also borne out by the charge density contours, thereby reinforcing the importance of amorphous cluster calculations in the understanding of the electronic structure of amorphous solids.

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ELECTRONIC STATES AND LOCAL DENSITY OF STATES NEAR GRAPHENE CORNER EDGE

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194512006058 ◽

2012 ◽

Vol 11 ◽

pp. 151-156 ◽

Cited By ~ 1

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.

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Supersymmetric Cluster Expansions and Applications to Random Schrödinger Operators

Mathematical Physics Analysis and Geometry ◽

10.1007/s11040-021-09375-5 ◽

2021 ◽

Vol 24 (1) ◽

Author(s):

Luca Fresta

Keyword(s):

Density Of States ◽

Local Density ◽

Schrödinger Operators ◽

Random Schrödinger Operators ◽

Schrodinger Operators ◽

Local Density Of States ◽

Weak Disorder ◽

Cluster Expansions ◽

Strong Disorder ◽

Lifshitz Tail

AbstractWe study discrete random Schrödinger operators via the supersymmetric formalism. We develop a cluster expansion that converges at both strong and weak disorder. We prove the exponential decay of the disorder-averaged Green’s function and the smoothness of the local density of states either at weak disorder and at energies in proximity of the unperturbed spectrum or at strong disorder and at any energy. As an application, we establish Lifshitz-tail-type estimates for the local density of states and thus localization at weak disorder.

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Near-Field Excitation of Bound States in the Continuum in All-Dielectric Metasurfaces through a Coupled Electric/Magnetic Dipole Model

Nanomaterials ◽

10.3390/nano11040998 ◽

2021 ◽

Vol 11 (4) ◽

pp. 998

Author(s):

Diego R. Abujetas ◽

José A. Sánchez-Gil

Keyword(s):

Magnetic Dipole ◽

Density Of States ◽

Bound States ◽

Local Density ◽

Near Field ◽

Field Pattern ◽

Local Density Of States ◽

Optical Modes ◽

Source Excitation ◽

The Continuum

Resonant optical modes arising in all-dielectric metasurfaces have attracted much attention in recent years, especially when so-called bound states in the continuum (BICs) with diverging lifetimes are supported. With the aim of studying theoretically the emergence of BICs, we extend a coupled electric and magnetic dipole analytical formulation to deal with the proper metasurface Green function for the infinite lattice. Thereby, we show how to excite metasurface BICs, being able to address their near-field pattern through point-source excitation and their local density of states. We apply this formulation to fully characterize symmetry-protected BICs arising in all-dielectric metasurfaces made of Si nanospheres, revealing their near-field pattern and local density of states, and, thus, the mechanisms precluding their radiation into the continuum. This formulation provides, in turn, an insightful and fast tool to characterize BICs (and any other leaky/guided mode) near fields in all-dielectric (and also plasmonic) metasurfaces, which might be especially useful for the design of planar nanophotonic devices based on such resonant modes.

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MODIFICATION OF CASIMIR FORCES DUE TO BAND GAPS IN PERIODIC STRUCTURES

International Journal of Modern Physics A ◽

10.1142/s0217751x02010145 ◽

2002 ◽

Vol 17 (06n07) ◽

pp. 798-803 ◽

Cited By ~ 7

Author(s):

C. VILLARREAL ◽

R. ESQUIVEL-SIRVENT ◽

G. H. COCOLETZI

Keyword(s):

Density Of States ◽

Casimir Force ◽

Periodic Structures ◽

Local Density ◽

Band Gaps ◽

Basic Unit ◽

Local Density Of States ◽

Casimir Forces ◽

Unit Cells ◽

The Difference

The Casimir force between inhomogeneous slabs that exhibit a band-like structure is calculated. The slabs are made of basic unit cells each made of two layers of different materials. As the number of unit cells increases the Casimir force between the slabs changes, since the reflectivity develops a band-like structure characterized by frequency regions of high reflectivity. This is also evident in the difference of the local density of states between free and boundary distorted vacuum, that becomes maximum at frequencies corresponding to the band gaps. The calculations are restricted to vacuum modes with wave vectors perpendicular to the slabs.

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Checkerboard local density of states in striped domains pinned by vortices

Physical Review B ◽

10.1103/physrevb.67.134528 ◽

2003 ◽

Vol 67 (13) ◽

Cited By ~ 21

Author(s):

Brian Møller Andersen ◽

Per Hedegård ◽

Henrik Bruus

Keyword(s):

Density Of States ◽

Local Density ◽

Local Density Of States

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Local Density of States of One-Dimensional Mott Insulators and Charge-Density Wave States with a Boundary

Physical Review Letters ◽

10.1103/physrevlett.101.086403 ◽

2008 ◽

Vol 101 (8) ◽

Cited By ~ 16

Author(s):

Dirk Schuricht ◽

Fabian H. L. Essler ◽

Akbar Jaefari ◽

Eduardo Fradkin

Keyword(s):

Charge Density ◽

Density Of States ◽

Charge Density Wave ◽

Local Density ◽

Density Wave ◽

Mott Insulators ◽

Local Density Of States ◽

One Dimensional ◽

Wave States

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Inferring effective interactions from the local density of states: Application to STM data fromBi2Sr2CaCu2O8+δ

Physical Review B ◽

10.1103/physrevb.74.174521 ◽

2006 ◽

Vol 74 (17) ◽

Cited By ~ 7

Author(s):

R. Jamei ◽

J. Robertson ◽

E-A. Kim ◽

A. Fang ◽

A. Kapitulnik ◽

...

Keyword(s):

Density Of States ◽

Local Density ◽

Local Density Of States ◽

Effective Interactions

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

Modern Physics Letters B ◽

10.1142/s0217984904007463 ◽

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.

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