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

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.

2012 ◽  
Vol 11 ◽  
pp. 151-156 ◽  
Author(s):  
YUJI SHIMOMURA ◽  
YOSITAKE TAKANE ◽  
KATSUNORI WAKABAYASHI

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.


2004 ◽  
Vol 18 (18) ◽  
pp. 955-962
Author(s):  
MUSA EL-HASAN ◽  
REZEK ESTATIEH

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.


2018 ◽  
Vol 9 ◽  
pp. 520-529 ◽  
Author(s):  
Jie Liu ◽  
Tiantian Yu ◽  
Juntao Song

We study theoretically the local density of states (DOS) in a topological Josephson junction. We show that the well-known 4π Josephson effect originates from the interference effect between two Majorana fermions (MFs) that are localized at the Josephson junction. In addition, the DOS for electrons (holes) shows the 4π interference information along each parity conserved energy spectrum. The DOS displays a 2π period oscillation when two trivial states interfere with each other. This means that the DOS information may be used to distinguish the MFs from trivial localized states. We suggest that the interference effect and the DOS can be detected by using two STM leads or two normal leads. A single side lead can only detect the Andreev reflection tunneling process in the junction, which cannot reveal information about the interference effect in general. However, using two side leads, we can reveal information about the interference effect of the MFs as well as the DOS by combining Andreev reflection with the electron transmission process.


1988 ◽  
Vol 38 (14) ◽  
pp. 9511-9516 ◽  
Author(s):  
Keith L. Peterson ◽  
J. S. Hsiao ◽  
D. R. Chopra ◽  
T. R. Dillingham

1997 ◽  
Vol 11 (09) ◽  
pp. 1187-1193 ◽  
Author(s):  
Chih-Kai Yang

An ab initio method is developed to calculate the surface electronic structure. The method is based on the tight-binding linear muffin-tin orbitals and real-space recursive Green's function and can achieve self-consistency efficiently. Sample calculations include Fe(001)and Cr(001) systems and are compared with recent experiments using scanning tunneling microscope and photoemission. From the calculated local density of states several prominent surface states above and below the Fermi level are identified and found to agree well with the experimental results.


Respuestas ◽  
2018 ◽  
Vol 23 (1) ◽  
pp. 13
Author(s):  
Hernan Javier Herrera ◽  
A. Rubio Ponce ◽  
D. Olguín

 La motivación del presente trabajo se fundamenta en la importancia del Paladio en procesos de catálisis y sus propiedades electrónicas. En tal sentido, se presenta un estudio detallado de la estructura electrónica de bandas del Paladio en la dirección cristalográfica (111). De tal manera, se verificó que la densidad local de estados proyectada en el volumen, concordara con los resultados obtenidos para el caso del medio infinito previamente reportados, para ello, se realizó un estudio detallado de diferentes estados de superficie y estados resonantes característicos del Paladio en la dirección cristalográfica (111). Se halló que los resultados obtenidos se comparan con los valores publicados en la literatura, y se hizo la predicción de diferentes estados no reportados aún.Palabras clave:  Estados de superficie, estados resonantes, estructura electrónica de bandas. AbstractThe motivation of this work is based on the importance of Palladium in processes such as catalysis and hence the need to know its electronic properties. We present a detailed study of the electronic structure of Palladium bands in the crystallographic direction (111). First we verify that the local density of states, projected in the volume, agrees with the results obtained for the case of the infinite medium previously reported. Next, a detailed study is made of different surface states and characteristic resonant states of the Palladium in the crystallographic direction (111). It was found that the results obtained are compared with the values published in the literature, and the prediction of different states not yet reported is made.Keywords: Surface states, resonant states, local density of states, bulk projected electronic band structure. ResumoA motivação do presente trabalho baseia-se na importância do paládio nos processos de catálise e suas propriedades eletrônicas. A este respeito, um estudo detalhado da estrutura eletrônica das bandas de paládio na direção cristalográfica (111) é apresentado. Desta forma, verificou-se que a densidade local de estados projetados no volume, vai concordar com os resultados obtidos para o caso do meio infinito relatado anteriormente, para isso, foi feito um estudo detalhado dos diferentes estados de superfície e estados ressonantes característicos do paládio. na direção cristalográfica (111). Verificou-se que os resultados obtidos são comparados com os valores publicados na literatura, e a predição dos diferentes estados ainda não relatados foi feita.Palavras-chave:  Estados de superfície, estados ressonantes, estrutura de banda eletrônica. 


1997 ◽  
Vol 491 ◽  
Author(s):  
J. J. Hogan-O'Neill ◽  
A. M. Martin ◽  
James F. Annett

ABSTRACTWe examine the effects of grain-boundaries on the order-parameter and critical-currents in superconductors. We use a geometrical model of the lattice structure of grain-boundaries. We solve the Bogoliubov-de Gennes equation using the Recursion Method to obtain the self-consistent BCS gap function Δ and the local density of states N(E) near the boundary. Imposing a phase difference across the boundary we calculate the supercurrent and hence obtain the critical-current, Ic, of the junction.


2021 ◽  
Vol 24 (1) ◽  
Author(s):  
Luca Fresta

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.


Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 998
Author(s):  
Diego R. Abujetas ◽  
José A. Sánchez-Gil

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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