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

1992 ◽  
Vol 291 ◽  
Author(s):  
Ariel A. Valladares ◽  
L. Enrique Sansores

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.

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.


1990 ◽  
Vol 209 ◽  
Author(s):  
L. Enrique Sansores ◽  
R.M. Valladares ◽  
J.A. Cogordan ◽  
A.A. Valladares

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.


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. 


2006 ◽  
Vol 75 (8) ◽  
pp. 083708 ◽  
Author(s):  
Tadashi Machida ◽  
Yusuke Kamijo ◽  
Keiji Harada ◽  
Tetsurou Noguchi ◽  
Ryo Saito ◽  
...  

2014 ◽  
Vol 1015 ◽  
pp. 155-158
Author(s):  
Wei Hua Wang ◽  
Cui Lan Zhao ◽  
Xin Jun Ma

The centre Au-doped armchair graphene nanoribbons (AGNRs) are investigated using the local density approximation based on density function theory. The charge density, electronic energy band and project density of states of centre Au-doped AGNRs are calculated. Our results indicate the charge density is transferred between C and Au atoms and mainly located on the Au atoms. The centre Au-doped AGNRs are an indirect band gap semiconductor with an energy gap of 1.046 eV. The Fermi level is located on valence band so that the AGNRs of doping Au become into degenerate semiconductor. The project density of states is calculated to reveal localization and hybridization between C-2pand Au-6s, 5delectronic states. The localization and hybridization are much stronger in the valence band. The hybridization between C-2pand Au-6pelectronic states are strongly in the conduction band.


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