Download or read book First principles Calculations and Model Hamiltonian Approaches to Electronic and Optical Properties of Defects Interfaces and Nanostructures written by Sangkook Choi and published by . This book was released on 2013 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamics of electrons governed by the Coulomb interaction determines a large portion of the observed phenomena of condensed matter. Thus, the understanding of electronic structure has played a key role in predicting the electronic and optical properties of materials. In this dissertation, I present some important applications of electronic structure theories for the theoretical calculation of these properties. In the first chapter, I review the basics necessary for two complementary electronic structure theories: model Hamiltonian approaches and first principles calculation. In the subsequent chapters, I further discuss the applications of these approaches to nanostructures (chapter II), interfaces (chapter III), and defects (chapter IV). The abstract of each section is as follows. Section II-1 The sensitive structural dependence of the optical properties of single-walled carbon nanotubes, which are dominated by excitons and tunable by changing diameter and chirality, makes them excellent candidates for optical devices. Because of strong many-electron interaction effects, the detailed dependence of the optical oscillator strength of excitons on nanotube diameter, chiral angle, and electronic subband index (the so-called family behavior) however has been unclear. In this study, based on results from an extended Hubbard Hamiltonian with parameters derived from ab initio GW-BSE calculations, we have obtained an explicit formula for the family behavior of the oscillator strengths of excitons in semiconducting single-walled carbon nanotubes (SWCNTs), incorporating environmental screening. The formula explains well recent measurements, and is expected to be useful in the understanding and design of possible SWCNT optical and optoelectronic devices. Section II-2 Wave supercollimation, in which a wavepacket is guided to move undistorted along a selected direction, is a highly desirable property that is difficult to achieve for photons and has yet to be experimentally seen for electrons. Disorder in a medium would inhibit supercollimation. Here, we report a counter-intuitive phenomenon of electron supercollimation by disorder in graphene, made possible by its Dirac fermion states. We show that one can use one-dimensional disorder potentials to control electron wavepacket transport along the potential fluctuation direction. This is distinct from all known systems where the wavepacket would be further spread by the disorder and hindered in the potential fluctuating direction. This phenomenon has significant implications in the understanding and applications of transport in graphene and other Dirac fermion materials. Section III-1 The origin of magnetic flux noise in superconducting quantum interference devices with a power spectrum scaling as 1 / f ( f is frequency) has been a puzzle for over 20 years. This noise limits the decoherence time of superconducting qubits. A consensus has emerged that the noise arises from fluctuating spins of localized electrons with an areal density of 5×1017 m−2. We show that the physical origin of the phenomenon are localized metal-induced gap states at the interface. In the presence of potential disorder at the metal-insulator interface, some of the metal-induced gap states become localized and produce local moments. A modest level of disorder yields the observed areal density. Section III-2 We present a microscopic theory of disorder-induced magnetic moment generation at nonmagnetic metal-insulator interfaces. Screened Hartree-Fock solution of a tight-binding Hamiltonian with electron-electron interaction, in which disorder is mimicked by the Anderson disorder model, shows that magnetic moments are originated from localized metal-induced gap states at the interface. Magnetic moment areal density becomes saturated at a maximum value of 4×1017 m−2 as the disorder magnitude increases, consistent with the observed universality of measured local magnetic moment areal density. Dielectric screening effect is found to be essential for understanding the relatively universal behavior of the observed value. Section IV-1 Optical initialization of the negatively charged nitrogen-vacancy (NV−) center in diamond makes it one of the best candidates for realization of addressable spins in the solid state for quantum computing and other studies. However, its exact mechanism was not clear. We show that exact diagonalization of a many-electron Hamiltonian with parameters derived from ab initio GW calculations puts strong constraints on the mechanism. The energy surfaces of the low-energy many-body states and the relaxation processes of photo-excitation responsible for the optical initialization are calculated. Intersystem crossings are shown to be essential Section IV-2 Graphene has been predicted to be a good test material for atomic collapse theory due to its linear band structure with a Fermi velocity 300 times slower than the speed of light. The Crommie group at UC Berkeley measured, using scanning tunneling microscopy, electrons bound to the positively charged calcium dimers on graphene, which corresponds to electrons collapsed to the super-heavy nucleus in artificial atoms. To compare measured bound states to atomic collapse theory in an artificial atom on graphene, the net charges associated with calcium dimers should be quantified. Here, we quantified the net charges associated with a calcium dimer using density function theory.
Download or read book Multi Band Effective Mass Approximations written by Matthias Ehrhardt and published by Springer. This book was released on 2014-07-17 with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses several mathematical models from the most relevant class of kp-Schrödinger systems. Both mathematical models and state-of-the-art numerical methods for adequately solving the arising systems of differential equations are presented. The operational principle of modern semiconductor nano structures, such as quantum wells, quantum wires or quantum dots, relies on quantum mechanical effects. The goal of numerical simulations using quantum mechanical models in the development of semiconductor nano structures is threefold: First they are needed for a deeper understanding of experimental data and of the operational principle. Secondly, they allow us to predict and optimize in advance the qualitative and quantitative properties of new devices in order to minimize the number of prototypes needed. Semiconductor nano structures are embedded as an active region in semiconductor devices. Thirdly and finally, the results of quantum mechanical simulations of semiconductor nano structures can be used with upscaling methods to deliver parameters needed in semi-classical models for semiconductor devices, such as quantum well lasers. This book covers in detail all these three aspects using a variety of illustrative examples. Readers will gain detailed insights into the status of the multiband effective mass method for semiconductor nano structures. Both users of the kp method as well as advanced researchers who want to advance the kp method further will find helpful information on how to best work with this method and use it as a tool for characterizing the physical properties of semiconductor nano structures. The book is primarily intended for graduate and Ph.D. students in applied mathematics, mathematical physics and theoretical physics, as well as all those working in quantum mechanical research or the semiconductor / opto-electronic industry who are interested in new mathematical aspects.
Download or read book Optical Properties of Nanostructures written by Ying Fu and published by CRC Press. This book was released on 2011-08-08 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses electrons and photons in and through nanostructures by the first-principles quantum mechanical theories and fundamental concepts (a unified coverage of nanostructured electronic and optical components) behind nanoelectronics and optoelectronics, the material basis, physical phenomena, device physics, as well as designs and applications. The combination of viewpoints presented in the book can help foster further research and cross-disciplinary interaction needed to surmount the barriers facing future generations of technology design.
Download or read book Silicon Nanocrystals written by Lorenzo Pavesi and published by John Wiley & Sons. This book was released on 2010-02-02 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt: This unique collection of knowledge represents a comprehensive treatment of the fundamental and practical consequences of size reduction in silicon crystals. This clearly structured reference introduces readers to the optical, electrical and thermal properties of silicon nanocrystals that arise from their greatly reduced dimensions. It covers their synthesis and characterization from both chemical and physical viewpoints, including ion implantation, colloidal synthesis and vapor deposition methods. A major part of the text is devoted to applications in microelectronics as well as photonics and nanobiotechnology, making this of great interest to the high-tech industry.
Download or read book Hamiltonian Methods in the Theory of Solitons written by Ludwig Faddeev and published by Springer Science & Business Media. This book was released on 2007-08-10 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main characteristic of this classic exposition of the inverse scattering method and its applications to soliton theory is its consistent Hamiltonian approach to the theory. The nonlinear Schrödinger equation is considered as a main example, forming the first part of the book. The second part examines such fundamental models as the sine-Gordon equation and the Heisenberg equation, the classification of integrable models and methods for constructing their solutions.
Download or read book Monte Carlo Methods for Radiation Transport written by Oleg N. Vassiliev and published by Springer. This book was released on 2016-10-17 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a guide to the use of Monte Carlo techniques in radiation transport. This topic is of great interest for medical physicists. Praised as a "gold standard" for accurate radiotherapy dose calculations, Monte Carlo has stimulated a high level of research activity that has produced thousands of papers within the past few years. The book is designed primarily to address the needs of an academically inclined medical physicist who wishes to learn the technique, as well as experienced users of standard Monte Carlo codes who wish to gain insight into the underlying mathematics of Monte Carlo algorithms. The book focuses on the fundamentals—giving full attention to and explaining the very basic concepts. It also includes advanced topics and covers recent advances such as transport of charged particles in magnetic fields and the grid-based solvers of the Boltzmann equation.
Download or read book A Method for Studying Model Hamiltonians written by Nikolaĭ Nikolaevich Bogoli︠u︡bov and published by Franklin Book Company. This book was released on 1972 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Method for Studying Model Hamiltonians: A Minimax Principle for Problems in Statistical Physics centers on methods for solving certain problems in statistical physics which contain four-fermion interaction. Organized into four chapters, this book begins with a presentation of the proof of the asymptotic relations for the many-time correlation functions. Chapter 2 details the construction of a proof of the generalized asymptotic relations for the many-time correlation averages. Chapter 3 explains the correlation functions for systems with four-fermion negative interaction. The last chapter sh ...
Download or read book Electronic Structure written by Richard M. Martin and published by Cambridge University Press. This book was released on 2004-04-08 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important graduate textbook in condensed matter physics by highly regarded physicist.
Download or read book First principles Calculations in Real space Formalism written by Kikuji Hirose and published by World Scientific. This book was released on 2005 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: With cutting-edge materials and minute electronic devices being produced by the latest nanoscale fabrication technology, it is essential for scientists and engineers to rely on first-principles (ab initio) calculation methods to fully understand the electronic configurations and transport properties of nanostructures. It is now imperative to introduce practical and tractable calculation methods that accurately describe the physics in nanostructures suspended between electrodes.This timely volume addresses novel methods for calculating electronic transport properties using real-space formalisms free from geometrical restrictions. The book comprises two parts: The first details the basic formalism of the real-space finite-difference method and its applications. This provides the theoretical foundation for the second part of the book, which presents the methods for calculating the properties of electronic transport through nanostructures sandwiched by semi-infinite electrodes.
Download or read book Theory of Electronic States and Formations Energies of Defect Complexes Interstitial Defects and Crystal Growth in Semiconductors written by O. F. Sankey and published by . This book was released on 1989 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first version of an ab-initio molecular dynamics computer code can simulate the motion of atoms at a surface and in the bulk of a semiconductor. Newton's equation for the nuclei, F = ma is combined with the Schrodinger equation for the electrons, HPsi=EPsi, to obtain a uniform picture of a covalent system dynamical properties. This document will list some of the performed simulations. A tight-binding method is developed with tight binding matrix elements calculated entirely from first principles. No fitting to experiment of any quantities is needed or done. This tight binding Hamiltonian will calculate the electronic structure of the material. The electronic structure theory is based on the local density approximation (LDA), with no adjustable parameters. The use of approximations is essential to having a method which is fast enough to be useful for simulation of medium and large size systems. Where possible, the results are compared to experimental data and find agreement consistent with the LDA. (jhd).
Download or read book First principles Electronic Structure Calculations written by Timo Korhonen and published by . This book was released on 1996 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics of Surfaces and Interfaces written by Harald Ibach and published by Springer Science & Business Media. This book was released on 2006-11-18 with total page 653 pages. Available in PDF, EPUB and Kindle. Book excerpt: This graduate-level textbook covers the major developments in surface sciences of recent decades, from experimental tricks and basic techniques to the latest experimental methods and theoretical understanding. It is unique in its attempt to treat the physics of surfaces, thin films and interfaces, surface chemistry, thermodynamics, statistical physics and the physics of the solid/electrolyte interface in an integral manner, rather than in separate compartments. It is designed as a handbook for the researcher as well as a study-text for graduate students. Written explanations are supported by 350 graphs and illustrations.
Download or read book Atomistic Spin Dynamics written by Olle Eriksson and published by Oxford University Press. This book was released on 2017 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several large experimental facilities that focus on detection and probing magnetization dynamics have been realized in Europe, USA and Japan. This book covers theoretical and practical aspects of the vibrant and emerging research field of magnetization dynamics.
Download or read book 2D Materials written by Phaedon Avouris and published by Cambridge University Press. This book was released on 2017-06-29 with total page 521 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn about the most recent advances in 2D materials with this comprehensive and accessible text. Providing all the necessary materials science and physics background, leading experts discuss the fundamental properties of a wide range of 2D materials, and their potential applications in electronic, optoelectronic and photonic devices. Several important classes of materials are covered, from more established ones such as graphene, hexagonal boron nitride, and transition metal dichalcogenides, to new and emerging materials such as black phosphorus, silicene, and germanene. Readers will gain an in-depth understanding of the electronic structure and optical, thermal, mechanical, vibrational, spin and plasmonic properties of each material, as well as the different techniques that can be used for their synthesis. Presenting a unified perspective on 2D materials, this is an excellent resource for graduate students, researchers and practitioners working in nanotechnology, nanoelectronics, nanophotonics, condensed matter physics, and chemistry.
Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory of Defects in Semiconductors written by David A. Drabold and published by Springer Science & Business Media. This book was released on 2007 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor science and technology is the art of defect engineering. The theoretical modeling of defects has improved dramatically over the past decade. These tools are now applied to a wide range of materials issues: quantum dots, buckyballs, spintronics, interfaces, amorphous systems, and many others. This volume presents a coherent and detailed description of the field, and brings together leaders in theoretical research. Today's state-of-the-art, as well as tomorrow’s tools, are discussed: the supercell-pseudopotential method, the GW formalism,Quantum Monte Carlo, learn-on-the-fly molecular dynamics, finite-temperature treatments, etc. A wealth of applications are included, from point defects to wafer bonding or the propagation of dislocation.
Download or read book The k p Method written by Lok C. Lew Yan Voon and published by Springer Science & Business Media. This book was released on 2009-06-06 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: I ?rst heard of k·p in a course on semiconductor physics taught by my thesis adviser William Paul at Harvard in the fall of 1956. He presented the k·p Hamiltonian as a semiempirical theoretical tool which had become rather useful for the interpre- tion of the cyclotron resonance experiments, as reported by Dresselhaus, Kip and Kittel. This perturbation technique had already been succinctly discussed by Sho- ley in a now almost forgotten 1950 Physical Review publication. In 1958 Harvey Brooks, who had returned to Harvard as Dean of the Division of Engineering and Applied Physics in which I was enrolled, gave a lecture on the capabilities of the k·p technique to predict and ?t non-parabolicities of band extrema in semiconductors. He had just visited the General Electric Labs in Schenectady and had discussed with Evan Kane the latter’s recent work on the non-parabolicity of band extrema in semiconductors, in particular InSb. I was very impressed by Dean Brooks’s talk as an application of quantum mechanics to current real world problems. During my thesis work I had performed a number of optical measurements which were asking for theoretical interpretation, among them the dependence of effective masses of semiconductors on temperature and carrier concentration. Although my theoretical ability was rather limited, with the help of Paul and Brooks I was able to realize the capabilities of the k·p method for interpreting my data in a simple way.
