A Model Dielectric Function for Semiconductors

1975 ◽  
Vol 53 (23) ◽  
pp. 2549-2554 ◽  
Author(s):  
R. D. Grimes ◽  
E. R. Cowley
Keyword(s):  
Dielectric Function ◽  
Energy Gap ◽  
Interpolation Formula ◽  
Electron System ◽  
Wave Functions ◽  
Three Dimensions ◽  
Energy Bands ◽  
One Dimensional ◽  
Energy Gaps ◽  
The Relationship

The microscopic dielectric function is calculated for a simple model of a semiconductor, originally proposed by Penn, in which the energy bands and wave functions are those of a one-dimensional, nearly free electron system, isotropically extended to three dimensions. The dielectric function is evaluated numerically so that all unnecessary approximations are avoided. The relationship between the static dielectric constant and the energy gap is found to be[Formula: see text]where S0 is about 0.6. The results for finite wave vectors, for a range of energy gaps, have been fitted to an interpolation formula to facilitate their use.

scholarly journals On the Nature of Electronic Wave Functions in One-Dimensional Self-Similar and Quasiperiodic Systems

2014 ◽  
Vol 2014 ◽  
pp. 1-35 ◽  
Author(s):  
Enrique Maciá
Keyword(s):  
Transport Properties ◽  
Wave Functions ◽  
Critical States ◽  
One Dimensional ◽  
Precise Nature ◽  
Self Similar ◽  
Electronic Wave Functions ◽  
Quasiperiodic Systems ◽  
The Relationship ◽  
Singular Continuous Spectra

The interest in the precise nature of critical states and their role in the physics of aperiodic systems has witnessed a renewed interest in the last few years. In this work we present a review on the notion of critical wave functions and, in the light of the obtained results, we suggest the convenience of some conceptual revisions in order to properly describe the relationship between the transport properties and the wave functions distribution amplitudes for eigen functions belonging to singular continuous spectra related to both fractal and quasiperiodic distribution of atoms through the space.

Electronic Structures of Oligomers of Pyrrole

2010 ◽  
Vol 663-665 ◽  
pp. 658-661 ◽  
Author(s):  
Bao Gai Zhai ◽  
Qing Lan Ma ◽  
Yuan Ming Huang
Keyword(s):  
Electronic Structures ◽  
Energy Gap ◽  
Tight Binding ◽  
One Dimensional ◽  
Extended Hückel ◽  
The Relationship ◽  
Green Photoluminescence

The electronic structures of oligomers of pyrrole have been calculated using the extended Hückel tight-binding program. The energy diagrams are shown for oligomers as the number of the repeating unit in the oligomers increases from 1 to 16. The relationship between the energy gap of the oligomers and the number of the repeating unit in the oligomers is established. Blue-green photoluminescence and electroluminescence from one-dimensional polypyrrole are predicted.

scholarly journals Effects of Organic Linkers on Energy gaps of Covalent based Triazine Frameworks

2018 ◽  
Vol 15 (11) ◽  
pp. 811-817
Author(s):  
Kamonrat KASORNMALA ◽  
Vittaya AMORNKITBAMRUNG ◽  
Pornjuk SREPUSHARAWOOT
Keyword(s):  
Optical Property ◽  
Benzene Ring ◽  
Energy Gap ◽  
Structural Parameters ◽  
Valence Band Maximum ◽  
Energy Bands ◽  
Energy Gaps ◽  
Indirect Band Gap ◽  
Band Gap Structure ◽  
Organic Linker

The Covalent Triazine Frameworks (CTFs) were successfully synthesized from the experiments. They usually consist of triazine ring covalently bonded with organic linkers. CTF-Benzene was defined in case of the organic linker be benzene ring. Moreover, 5 different types of organic linkers, namely, Napthalene, Quinoline, Quinoxaline, Anthracene and Acridine were chosen to connect to the boroxine ring and these structures are abbreviated as CTF-Naphthalene, CTF-Quinoline, CTF-Quinoxaline, CTF-Anthracene and CTF-Acridine, respectively. In the present study, the structural parameters, the density of states and energy bands of these structures were investigated by means of the first-principles calculations. For the CTF-Benzene structure, it shows an indirect band gap structure with energy gap of 1.86 eV. By considering the electron density at the states of valence band maximum and conduction band minimum, it was found that the electrons are only localized on the benzene ring. Hence, the optical property of this structure directly related to type of organic linker. This leads us to calculate the optical property of various types of the organic linker in order to adjust the optical property in the Covalent based Triazine Frameworks. According to CTF- Naphthalene, CTF-Quinoline and CTF-Quinoxaline structures, we found that the energy gap ranges from 1.0 to 1.5 eV. Moreover, our calculations revealed that the energy gaps of CTF- Anthracene CTF-Acridine are 0.40 and 0.75 eV, respectively. Based on these results, it is clearly seen that the optical band gaps of these CTF structures can be adjustable in range of 0.4 - 2.5 eV depending on the type of organic linker. Finally, we believed that these newly generated structures might be useful for both photovoltaic and solarcell applications.

‘Each Song Was Just Like a Little Sermon’

2018 ◽  
Author(s):  
Isaac Land
Keyword(s):  
Nineteenth Century ◽  
Golden Age ◽  
Military Training ◽  
One Dimensional ◽  
National Pride ◽  
Recent Scholarship ◽  
The Relationship

This chapter is central to the volume’s chronological contentions, as its argument accounts for the specialized, one-dimensional Dibdin of ‘Tom Bowling’ that has endured into recent scholarship. Focusing on Dibdin’s posthumous reception, it examines the moral and rhetorical difficulties of repackaging Dibdin’s works for a Victorian sensibility; it explores the specifics of mid-century concert culture previously highlighted by Derek Scott and William Weber as central to changes in nineteenth-century taste and programming; and it develops the theme of nostalgia into a revelatory consideration of the relationship between new naval technologies, national pride, and military training, and the songs, people, and language of a remembered Napoleonic ‘golden age’—to which Dibdin proves to have been as central, in the Victorian imagination, as Nelson.

Quantum Boxes, Stringed Instruments

2017 ◽  
Author(s):  
Frank S. Levin
Keyword(s):  
Energy Level ◽  
Schrödinger Equation ◽  
Quantum System ◽  
Schrodinger Equation ◽  
Probability Distributions ◽  
Wave Functions ◽  
Energy Level Diagram ◽  
One Dimensional ◽  
Stringed Instruments ◽  
Symmetry Properties

Chapter 7 illustrates the results obtained by applying the Schrödinger equation to a simple pedagogical quantum system, the particle in a one-dimensional box. The wave functions are seen to be sine waves; their wavelengths are evaluated and used to calculate the quantized energies via the de Broglie relation. An energy-level diagram of some of the energies is constructed; on it are illustrations of the corresponding wave functions and probability distributions. The wave functions are seen to be either symmetric or antisymmetric about the midpoint of the line representing the box, thereby providing a lead-in to the later exploration of certain symmetry properties of multi-electron atoms. It is next pointed out that the Schrödinger equation for this system is identical to Newton’s equation describing the vibrations of a stretched musical string. The different meaning of the two solutions is discussed, as is the concept and structure of linear superpositions of them.

Effect of mechanical restraint on the rate of corrosion in concrete

1998 ◽  
Vol 25 (1) ◽  
pp. 81-86 ◽  
Author(s):  
N Hearn ◽  
J Aiello
Keyword(s):  
Mix Design ◽  
Concrete Repair ◽  
Accelerated Corrosion ◽  
One Dimensional ◽  
Mechanical Restraint ◽  
Corrosion Rates ◽  
Accelerated Corrosion Tests ◽  
The Matrix ◽  
The Relationship

Experimental work on prismatic concrete specimens was conducted to determine the relationship between mechanical restraint and the rate of corrosion. The current together with the changes in strain of the confining frame were monitored during the accelerated corrosion tests. The effect of mix design and cracking on the corrosion rates was also investigated. The results show that one-dimensional mechanical restraint retards the corrosion process, as indicated by the reduction in the steel loss. Improved quality of the matrix, with and without cracking, reduces the rate of steel loss. In the inferior quality concrete, the effect of cracking on the corrosion rate is minimal.Key words: corrosion, concrete, repair.

scholarly journals Effect of Laser Irradiation on Emissivity of Flame-Generated Nanooxides

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2303
Author(s):  
Silvana De Iuliis ◽  
Roberto Dondè ◽  
Igor Altman
Keyword(s):  
Laser Irradiation ◽  
Light Emission ◽  
Energy Gap ◽  
Particle Temperature ◽  
Electron Excitation ◽  
Flame Spray ◽  
Energy Bands ◽  
Light Emitting ◽  
Spectral Behavior ◽  
The Difference

The application of pyrometry to retrieve particle temperature in particulate-generating flames strictly requires the knowledge of the spectral behavior of emissivity of light-emitting particles. Normally, this spectral behavior is considered time-independent. The current paper challenges this assumption and explains why the emissivity of oxide nanoparticles formed in flame can change with time. The suggested phenomenon is related to transitions of electrons between the valence and conduction energy bands in oxides that are wide-gap dielectrics. The emissivity change is particularly crucial for the interpretation of fast processes occurring during laser-induced experiments. In the present work, we compare the response of titania particles produced by a flame spray to the laser irradiation at two different excitation wavelengths. The difference in the temporal behavior of the corresponding light emission intensities is attributed to the different mechanisms of electron excitation during the laser pulse. Interband transitions that are possible only in the case of the laser photon energy exceeding the titania energy gap led to the increase of the electron density in the conduction band. Relaxation of those electrons back to the valence band is the origin of the observed emissivity drop after the UV laser irradiation.

scholarly journals Psychological contract breach and voluntary turnover among newcomers: the role of supervisor trustworthiness and negative affectivity

2021 ◽  
pp. 1-21
Author(s):  
Émilie Lapointe ◽  
Christian Vandenberghe
Keyword(s):  
Psychological Contract ◽  
Negative Affectivity ◽  
Voluntary Turnover ◽  
Three Dimensions ◽  
Psychological Contract Breach ◽  
Contract Breach ◽  
Indirect Relationship ◽  
Relationship Of ◽  
The Relationship

Abstract This article looks at the relationship between psychological contract breach and voluntary turnover among newcomers, using supervisor trustworthiness as a mediator and negative affectivity as a moderator. Relying on data from 243 newcomers, psychological contract breach was found to be negatively related to the three dimensions of supervisor trustworthiness, i.e., ability, benevolence, and integrity. Supervisor integrity further mediated a positive relationship between psychological contract breach and voluntary turnover measured 8 months later. Psychological contract breach interacted with negative affectivity such that it was less negatively related to dimensions of supervisor trustworthiness at high levels of negative affectivity. The indirect relationship of psychological contract breach to voluntary turnover as mediated by supervisor integrity was also weaker at high levels of negative affectivity. We discuss the implications of these findings for research and practice.

scholarly journals Topological correlators and surface defects from equivariant cohomology

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Rodolfo Panerai ◽  
Antonio Pittelli ◽  
Konstantina Polydorou
Keyword(s):  
Quantum Mechanics ◽  
Equivariant Cohomology ◽  
Surface Defects ◽  
Star Product ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Dimensional System ◽  
The Novel ◽  
One Dimensional ◽  
Dual Quantum

Abstract We find a one-dimensional protected subsector of $$ \mathcal{N} $$ N = 4 matter theories on a general class of three-dimensional manifolds. By means of equivariant localization we identify a dual quantum mechanics computing BPS correlators of the original model in three dimensions. Specifically, applying the Atiyah-Bott-Berline-Vergne formula to the original action demonstrates that this localizes on a one-dimensional action with support on the fixed-point submanifold of suitable isometries. We first show that our approach reproduces previous results obtained on S3. Then, we apply it to the novel case of S2× S1 and show that the theory localizes on two noninteracting quantum mechanics with disjoint support. We prove that the BPS operators of such models are naturally associated with a noncom- mutative star product, while their correlation functions are essentially topological. Finally, we couple the three-dimensional theory to general $$ \mathcal{N} $$ N = (2, 2) surface defects and extend the localization computation to capture the full partition function and BPS correlators of the mixed-dimensional system.

Statistical Mechanics of Thermotransport of a Heavy Impurity in an Insulating Solid

1971 ◽  
Vol 26 (1) ◽  
pp. 10-17 ◽  
Author(s):  
A. R. Allnatt
Keyword(s):  
Heat Flux ◽  
Time Correlation ◽  
Three Dimensions ◽  
Time Correlation Functions ◽  
Single Vacancy ◽  
One Dimensional ◽  
Enthalpy Of Activation ◽  
Heavy Impurity ◽  
The One ◽  
Non Equilibrium

AbstractA kinetic equation is derived for the singlet distribution function for a heavy impurity in a lattice of lighter atoms in a temperature gradient. In the one dimensional case the equation can be solved to find formal expressions for the jump probability and hence the heat of transport, q*. for a single vacancy jump of the impurity, q* is the sum of the enthalpy of activation, a term involving only averaging in an equilibrium ensemble, and two non-equilibrium terms in­volving time correlation functions. The most important non-equilibrium term concerns the cor­relation between the force on the impurity and a microscopic heat flux. A plausible extension to three dimensions is suggested and the relation to earlier isothermal and non-isothermal theories is indicated

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