MODIFICATION OF CASIMIR FORCES DUE TO BAND GAPS IN PERIODIC STRUCTURES

2002 ◽  
Vol 17 (06n07) ◽  
pp. 798-803 ◽  
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.

Ab Initio Molecular Dynamics Study of Al, Ga and Si Adsorption on the Si(001) Surface

1993 ◽  
Vol 318 ◽  
Author(s):  
T. Yamasaki ◽  
M. Ikeda ◽  
Y. Morikawa ◽  
K. Terakura
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Density Of States ◽  
Local Density ◽  
Ab Initio Molecular Dynamics ◽  
Local Density Of States ◽  
Mono Layer ◽  
The Difference ◽  
Stable Structures

ABSTRACTThe adsorption of Al, Ga and Si on the Si(001) surface is studied by the ab initio molecular dynamics (Car-Parrinello) method based on the norm-conserving pseudopotential. In the stable structures obtained for half mono-layer coverage( ө = 1/2), these ad-atoms form dimers, but the dimer configurations are different. Al and Ga atoms form parallel dimers whose dimerization direction is parallel to that of substrate Si-dimers, while adsorbed Si atoms form (dense) orthogonal dimers. The electronic origin of the difference in the stable configurations among Al, Ga and Si ad-atoms is analyzed by calculating the local density of states (LDOS) of each atom.

scholarly journals Supersymmetric Cluster Expansions and Applications to Random Schrödinger Operators

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.

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

Nanomaterials ◽  
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.

scholarly journals Checkerboard local density of states in striped domains pinned by vortices

2003 ◽  
Vol 67 (13) ◽  
Author(s):  
Brian Møller Andersen ◽  
Per Hedegård ◽  
Henrik Bruus
Keyword(s):  
Density Of States ◽  
Local Density ◽  
Local Density Of States

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

2006 ◽  
Vol 74 (17) ◽  
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

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.

Local Density of States of a Three-Dimensional Conductor in the Extreme Quantum Limit

2001 ◽  
Vol 86 (8) ◽  
pp. 1582-1585 ◽  
Author(s):  
D. Haude ◽  
M. Morgenstern ◽  
I. Meinel ◽  
R. Wiesendanger
Keyword(s):  
Density Of States ◽  
Local Density ◽  
Three Dimensional ◽  
Quantum Limit ◽  
Local Density Of States

scholarly journals Electrochemical Mapping Reveals Direct Correlation between Heterogeneous Electron-Transfer Kinetics and Local Density of States in Diamond Electrodes

2012 ◽  
Vol 124 (28) ◽  
pp. 7108-7112 ◽  
Author(s):  
Hollie V. Patten ◽  
Katherine E. Meadows ◽  
Laura A. Hutton ◽  
James G. Iacobini ◽  
Dario Battistel ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Density Of States ◽  
Local Density ◽  
Local Density Of States ◽  
Diamond Electrodes ◽  
Electron Transfer Kinetics ◽  
Heterogeneous Electron Transfer

Defected/decorated benzenoid/graphitic nanostructures

2008 ◽  
Vol 80 (7) ◽  
pp. 1399-1414 ◽  
Author(s):  
D. J. Klein
Keyword(s):  
Density Of States ◽  
Local Density ◽  
Valence Bond ◽  
Two Dimensions ◽  
Local Density Of States ◽  
Reliable Prediction ◽  
Vacancy Defects ◽  
Substitutional Defects ◽  
Local Defects ◽  
Property Characterization

Various decorations, functionalizations, or defects of conjugated benzenoid or graphitic networks are considered, with special attention to the case that the structures are possibly extended in one or two dimensions. This includes various polymers, their end structures, and defects of side groups or vacancies along the chain, strip, or nanotube. This approach further includes various boundary (or edge) structures on semi-infinite graphite, as well as various "quasi-local" defects in what is otherwise two-dimensionally infinite graphite, such defects encompassing vacancy defects, selected substitutional defects, and perhaps even dislocations and disclinations. There are many possible such nanostructures, but property characterization is ultimately desired. Attention is paid to consequent occurrences of defect-localized unpaired (or weakly paired) electrons, as formulated within a resonating valence bond (RVB) framework, especially as regards simple classically appealing theorems or rules. But a further molecular orbital (MO) view is developed. Note is made of associated modifications in the local density of states near the Fermi energy. Consonance of predictions from RVB and MO viewpoints is taken as an indicator of reliable prediction.

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