scholarly journals Surface and Core Electronic Structure of Oxidized Silicon Nanocrystals

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Noor A. Nama ◽  
Mudar A. Abdulsattar ◽  
Ahmed M. Abdul-Lettif
Keyword(s):  
Electronic Properties ◽  
Lattice Constant ◽  
Silicon Nanocrystals ◽  
Energy Gap ◽  
Surface Part ◽  
Hartree Fock ◽  
The Core ◽  
Conduction Bands ◽  
Quantum Confinement Effects ◽  
Core Part

Ab initio restricted Hartree-Fock method within the framework of large unit cell formalism is used to simulate silicon nanocrystals between 216 and 1000 atoms (1.6–2.65 nm in diameter) that include Bravais and primitive cell multiples. The investigated properties include core and oxidized surface properties. Results revealed that electronic properties converge to some limit as the size of the nanocrystal increases. Increasing the size of the core of a nanocrystal resulted in an increase of the energy gap, valence band width, and cohesive energy. The lattice constant of the core and oxidized surface parts shows a decreasing trend as the nanocrystal increases in a size that converges to 5.28 Ǻ in a good agreement with the experiment. Surface and core convergence to the same lattice constant reflects good adherence of oxide layer at the surface. The core density of states shows highly degenerate states that split at the oxygenated (001)-(1×1) surface due to symmetry breaking. The nanocrystal surface shows smaller gap and higher valence and conduction bands when compared to the core part, due to oxygen surface atoms and reduced structural symmetry. The smaller surface energy gap shows that energy gap of the nanocrystal is controlled by the surface part. Unlike the core part, the surface part shows a descending energy gap that proves its obedience to quantum confinement effects. Nanocrystal geometry proved to have some influence on all electronic properties including the energy gap.

Effect of the structural changes on the mechanical properties of the sintered films

2016 ◽  
Vol 12 (1) ◽  
pp. 4141-4144
Author(s):  
Garima Jain
Keyword(s):  
Crystallite Size ◽  
Lattice Constant ◽  
Structural Changes ◽  
Structural Investigation ◽  
Energy Gap ◽  
Lattice Parameter ◽  
Metal Chalcogenides ◽  
Optical Energy Gap ◽  
Tin Telluride ◽  
Physical Quantities

Polycrystalline films of tin telluride were prepared by sintering technique. The structural investigation of the films with different thicknesses enables to determine lattice parameter, crystallite size and strain existing in the films. The XRD traces showed that strain was tensile in nature. The crystallite size increases with thickness while strain decreases. Higher the value of tensile strain, larger is the lattice constant. The optical energy gap shows a descending nature with increasing strain and so with the lattice constant. Such an attempt made to delve into interdependence of basic physical quantities helps to explore the properties of SnTe and utilize it as an alternative to heavy metal chalcogenides in various technological applications.  

scholarly journals Morphological characterization and electronic properties of pristine and oxygen-exposed graphene nanoribbons on Ag(110)

2021 ◽  
Author(s):  
Jose Eduardo Barcelon ◽  
Marco Smerieri ◽  
Giovanni Carraro ◽  
Pawel Wojciechowski ◽  
Luca Vattuone ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Quantum Confinement ◽  
Energy Gap ◽  
Graphene Nanoribbons ◽  
Morphological Characterization

Graphene nanoribbons (GNRs) are at the frontier of research on graphene materials since the 1D quantum confinement of electrons allows for the opening of an energy gap.

scholarly journals Exploring a near-Hartree–Fock–Kohn–Sham approach to study electronic properties of azobenzene in interaction with gold: From clusters to the Au(111) surface

2020 ◽  
Vol 153 (21) ◽  
pp. 214701
Author(s):  
Gabriel F. Martins ◽  
Bernardo de P. Cardoso ◽  
Nuno Galamba ◽  
Benedito J. C. Cabral
Keyword(s):  
Electronic Properties ◽  
Hartree Fock

scholarly journals Extended analysis of Xe VII and Xe VIII

2017 ◽  
Vol 95 (9) ◽  
pp. 805-810 ◽  
Author(s):  
M. Raineri ◽  
M. Gallardo ◽  
J. Reyna Almandos ◽  
C.J.B. Pagan ◽  
R. Sarmiento
Keyword(s):  
Light Source ◽  
Energy Levels ◽  
Excited Configuration ◽  
Pulsed Discharge ◽  
Hartree Fock ◽  
The Core ◽  
New Energy ◽  
Extended Analysis ◽  
First Time ◽  
Atomic Parameters

A pulsed discharge light source to study the six and seven times ionized xenon spectra in the 419–4642 Å region was used. A set of 40 transitions of Xe VII and 25 transitions of Xe VIII were classified for the first time. We revised the values for the previously known energy levels and extended the analysis for Xe VII to 10 new energy levels belonging to 5s6d, 5s7s and 5s7p, 4d95s25p even and odd configurations, respectively. Seven new energy levels of the core excited configuration 4d95s5d of Xe VIII are presented. For the prediction of the atomic parameters, energy levels, and transition, relativistic Hartree–Fock calculations were used.

scholarly journals Microbiological aspects of biogenic amines formation in ripening cheeses

2007 ◽  
Vol 55 (4) ◽  
pp. 23-28
Author(s):  
Olga Cwiková ◽  
Vlastimil Dohnal ◽  
Tomáš Komprda
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Biogenic Amines ◽  
Starter Cultures ◽  
Part C ◽  
The Core ◽  
Edge Part ◽  
Core Part ◽  
Hard Cheese ◽  
Microbiological Aspects

Counts of lactic acid bacteria (LAB), total anaerobes and enterococci were determined in the course of ripening in the edge part (E) and the core part (C) of Dutch-type semi-hard cheese produced with different fat content (30 and 45 %) by two different producers (H and R) using two different starter cultures (L and Y). Counts of LAB at the beginning of ripening (day 0) in H producer´s samples were higher (P < 0,01) in comparison with the R producer´s ones. Count of enterococci was the highest (P < 0,05) at the end of the ripening (176th day) in sample R30YE. Higher (P < 0,01) enterococci counts were in R producer´s cheeses (in comparison with the H producer´s ones). Enterococci contamination was higher (P < 0,05) in E-samples than C-samples. Content of the sum of all BA in cheese was negatively correlated (P < 0,05) with counts of lactic acid bacteria (r = –0,24) and counts of total anaerobes (r = –0,23). No correlation between the sum of BA content and enterococci counts was found.

Design of Urban-Rural Power Grid Dispatching Fault Diagnosis Expert System

2014 ◽  
Vol 539 ◽  
pp. 659-663 ◽  
Author(s):  
Xiu Feng Xu
Keyword(s):  
Fault Diagnosis ◽  
Expert System ◽  
Automatic System ◽  
Power Grid ◽  
The Core ◽  
Scada System ◽  
Urban Rural ◽  
Fault Inference ◽  
Fault Information ◽  
Core Part

The paper designs the urban-rural power grid dispatching fault diagnosis expert system which acquires fault information by SCADA system of automatic system of urban-rural power grid, and uses artificial intellegence method to analyze fault information and make fault diagnosis. The paper implements the core part of the fault expert systemthe design of knowledge base and fault inference engine.

DFT STUDY OF STRUCTURAL AND ELECTRONIC PROPERTIES OF ENDOHEDRAL COMPLEXES OF GROUP V ATOMS WITH C60

2013 ◽  
Vol 27 (26) ◽  
pp. 1350152 ◽  
Author(s):  
AKSHU PAHUJA ◽  
SUNITA SRIVASTAVA
Keyword(s):  
Electronic Properties ◽  
Energy Gap ◽  
Central Atom ◽  
Energy Levels ◽  
Electronic Configuration ◽  
Group V ◽  
Foreign Atom ◽  
Endohedral Fullerenes ◽  
Endohedral Complexes ◽  
Structural And Electronic Properties

The structural and electronic properties of endohedral fullerenes formed by encapsulation of each of the group V elements inside the buckminsterfullerene cage have been investigated. The calculations reveal that all these species are thermodynamically stable, though the formation of Sb@C 60 and Bi@C 60 is slightly endothermic. The central atom preserves its electronic configuration and the quartet state. The energy gap and energy levels are perturbed by the inclusion of a foreign atom. The band gap of Sb@C 60 and Bi@C 60 is found to be significantly smaller than pristine C 60, suggesting the reactivity of these complexes.

Theoretical core spectroscopy of molecules interacting with ice surfaces 

2021 ◽  
Author(s):  
Richard Asamoah Opoku
Keyword(s):  
Electronic Properties ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Trace Gases ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Development Fund ◽  
Xps Spectra ◽  
The Core ◽  
Ice Surfaces

&lt;p&gt;&lt;strong&gt;C&amp;#233;line TOUBIN&lt;/strong&gt;&lt;strong&gt;&lt;sup&gt;2&lt;/sup&gt;&lt;/strong&gt;&lt;strong&gt; and &lt;/strong&gt;&lt;strong&gt;Andr&amp;#233; Severo Pereira GOMES&lt;/strong&gt;&lt;strong&gt;&lt;sup&gt; 3&lt;/sup&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;sup&gt;2,3&lt;/sup&gt; Laboratoire de Physique des Lasers, des atomes et des Mol&amp;#233;cules, Universit&amp;#233; de Lille, Cit&amp;#233; Scientifique, 59655 Villeneuve d&amp;#8217;Ascq Cedex, France&lt;/p&gt;&lt;p&gt;E-mail : [email protected]&lt;sup&gt;2&lt;/sup&gt; ; [email protected]&lt;sup&gt;3&lt;/sup&gt;&lt;/p&gt;&lt;p&gt;Ice plays an essential role as a catalyst for reactions between atmospheric trace gases. The uptake of trace gases to ice has been proposed to have a major impact on geochemical cycles, human health, and ozone depletion in the stratosphere [1]. X-ray photoelectron spectroscopy (XPS) [2], serves as a powerful technique to characterize the elemental composition of such interacting species due to its surface sensitivity. Given the existence of complex physico-chemical processes such as adsorption, desorption, and migration within ice matrix, it is important to establish a theoretical framework to determine the electronic properties of these species under different conditions such as temperature and concentration. The focus of this work is to construct an embedding methodology employing Density Functional (DFT) and Wave Function Theory (WFT) to model and interpret photoelectron spectra of adsorbed halogenated species on ice surfaces at the core level with the highest accuracy possible.&amp;#160;&lt;/p&gt;&lt;p&gt;We make use of an embedding approach utilizing full quantum mechanics to divide the system into subunits that will be treated at different levels of theory [3].&lt;/p&gt;&lt;p&gt;The goal is to determine core electron binding energies and the associated chemical shifts for the adsorbed halogenated species such as molecular HCl and the dissociated form Cl- at the surface and within the uppermost bulk layer of the ice respectively [4]. The core energy shifts are compared to the data derived from the XPS spectra [4].&lt;/p&gt;&lt;p&gt;We show that the use of a fully quantum mechanical embedding method, to treat solute-solvent systems is computationally efficient, yet accurate enough to determine the electronic properties of the solute system (halide ion) as well as the long-range effects of the solvent environment (ice).&lt;/p&gt;&lt;p&gt;We acknowledge support by the French government through the Program &amp;#8220;Investissement d'avenir&amp;#8221; through the Labex CaPPA (contract ANR-11-LABX-0005-01) and I-SITE ULNE project OVERSEE (contract ANR-16-IDEX-0004), CPER CLIMIBIO (European Regional Development Fund, Hauts de France council, French Ministry of Higher Education and Research) and French national supercomputing facilities (grants DARI x2016081859 and A0050801859).&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Low resistant and stable lithium-garnet electrolyte interface enabled by a multifunctional anode additive for solid-state lithium batteries

2021 ◽  
Author(s):  
Chencheng Cao ◽  
Yijun Zhong ◽  
Kimal Chandula Wasalathilake ◽  
Moses O. Tade ◽  
Xiaomin Xu ◽  
...  
Keyword(s):  
Solid State ◽  
Energy Density ◽  
Lithium Batteries ◽  
The Core ◽  
Intrinsic Stability ◽  
Electrolyte Interface ◽  
Lithium Garnet ◽  
Solid State Batteries ◽  
Core Part

Solid-state batteries (SSBs) have attracted considerable attention due to the high intrinsic stability and theoretical energy density. As the core part, garnet electrolyte has been extensively investigated due to high...

Interoperability Issues for Systems Managing Competency Information

2010 ◽  
pp. 83-105
Author(s):  
Bernard Blandin ◽  
Geoffrey Frank ◽  
Simone Laughton ◽  
Kenji Hirata
Keyword(s):  
Supply Chain ◽  
Final Section ◽  
Reference Model ◽  
Research Programme ◽  
Semantic Model ◽  
Research Directions ◽  
The Third ◽  
The Core ◽  
Digital Services ◽  
Core Part

This chapter has four sections. The first one describes how the needs for interoperability in exchanging competency information have been addressed so far. The second part adopts a “Digital Services Supply Chain” approach and discusses the issues related to the exchange of competency information across systems regarding this approach. The third part is the core part of this chapter. It describes the 4 levels of the proposed approach: the Conceptual Reference Model (CRM), the Semantic Model, the Information Model and the Data Model. The final section presents the research directions currently envisaged, and the research programme needed to make the proposed approach operational.

Sign in / Sign up

Export Citation Format

Share Document