Download or read book Exchange and Correlation Effects in an Inhomogeneous Electron Gas written by W. Kohn and published by . This book was released on 1965 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: From a theory of Hohenberg and Kohn, approximation methods for treating an inhomogeneous system of interacting electrons are developed. They lead to selfconsistent equations analagous to the Hartree and HartreeFock equations, respectively. In these equations the exchange and correlation portions of the chemical potential of a uniform electron gas appear as corrections to the electrostatic potential. (Author).

Download or read book Theory of the Inhomogeneous Electron Gas written by Stig Lundqvist and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 405 pages. Available in PDF, EPUB and Kindle. Book excerpt: The theory of the inhomogeneous electron gas had its origin in the Thomas Fermi statistical theory, which is discussed in the first chapter of this book. This already leads to significant physical results for the binding energies of atomic ions, though because it leaves out shell structure the results of such a theory cannot reflect the richness of the Periodic Table. Therefore, for a long time, the earlier method proposed by Hartree, in which each electron is assigned its own personal wave function and energy, dominated atomic theory. The extension of the Hartree theory by Fock, to include exchange, had its parallel in the density description when Dirac showed how to incorporate exchange in the Thomas-Fermi theory. Considerably later, in 1951, Slater, in an important paper, showed how a result similar to but not identical with that of Dirac followed as a simplification of the Hartree-Fock method. It was Gombas and other workers who recognized that one could also incorporate electron correlation consistently into the Thomas-Fermi-Dirac theory by using uniform electron gas relations locally, and progress had been made along all these avenues by the 1950s.

Download or read book Many body Theory of a Rapidly Varying Inhomogeneous Electron Gas written by John William Gadzuk and published by . This book was released on 1968 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: The case of an inhomogeneous electron gas within which the density variation is significant over a spatial range of the order of a Fermi wave-length is considered in this report. It is seen that for most systems of physical interest, this sort of non-uniformity is a result of diffraction effects. This is a fundamentally different phenomenon than can reasonably be treated by the density gradient method of Kohn for slowly varying inhomogeneous electron gases. Several sample cases are treated. The first considerations are directed towards the problem of a weak periodic potential in an interacting electron gas. The momentum-dependent self-energy is calculated for an electron propagating in the many-body medium of an electron gas plus a periodic lattice pseudo-potential. This is the equivalent of a quasi-particle energy spectrum and thus an orthogonalized plane wave energy band. It does not appear that the lattice drastically changes qualitative aspects of plane wave many-body theory. A dielectric formulation for a general inhomogeneous electron gas is presented. By introducing a new image technique, the dielectric function within the random phase approximation, which is valid in the surface region of an electron gas, is obtained. A Green's function formalism is developed for treating the static dielectric screening of a point impurity in an electron gas. The surface dielectric function is used with the impurity screening formalism to treat the problem of impurity screening in the surface region. This is an idealized model of ionic adsorption on metal surface. Screening charge densities resulting from volume polarization effects are calculated. From these results, it is seen why unjustifiable application of classical image forces in previous adsorption theories has fortunately produced reasonable results. A new method for obtaining the appropriate plasmon contribution to the electron self-energy in the surface region is developed. With these results, the electron gas surface potentials calculated by Loucks and Cutler are then improved.

Download or read book Self consistent Equations Including Exchange and Correlation Effects written by Walter Kohn and published by . This book was released on 1965 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: From a theory of Hohenberg and Kohn, approximation methods for treating an inhomogeneous system of interacting electrons are developed. These methods are exact for systems of slowly varying or high density. For the ground state, they lead to self-consistent equations analogous to the Hartree and Hartree-Fock equations, respectively. In these equations the exchange and correlation portions of the chemical potential of a uniform electron gas appear as additional effective potentials. (The exchange portion of our effective potential differs from that due to Slater by a factor of 2/3.) Electronic systems at finite temperatures and in magnetic fields are also treated by similar methods. An appendix deals with a further correction for systems with short wavelength density oscillations. (Author).

Download or read book Frontiers and Challenges in Warm Dense Matter written by Frank Graziani and published by Springer Science & Business. This book was released on 2014-04-28 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Warm Dense Matter (WDM) occupies a loosely defined region of phase space intermediate between solid, liquid, gas, and plasma, and typically shares characteristics of two or more of these phases. WDM is generally associated with the combination of strongly coupled ions and moderately degenerate electrons, and careful attention to quantum physics and electronic structure is essential. The lack of a small perturbation parameter greatly limits approximate attempts at its accurate description. Since WDM resides at the intersection of solid state and high energy density physics, many high energy density physics (HEDP) experiments pass through this difficult region of phase space. Thus, understanding and modeling WDM is key to the success of experiments on diverse facilities. These include the National Ignition Campaign centered on the National Ignition Facility (NIF), pulsed-power driven experiments on the Z machine, ion-beam-driven WDM experiments on the NDCX-II, and fundamental WDM research at the Linear Coherent Light Source (LCLS). Warm Dense Matter is also ubiquitous in planetary science and astrophysics, particularly with respect to unresolved questions concerning the structure and age of the gas giants, the nature of exosolar planets, and the cosmochronology of white dwarf stars. In this book we explore established and promising approaches to the modeling of WDM, foundational issues concerning the correct theoretical description of WDM, and the challenging practical issues of numerically modeling strongly coupled systems with many degrees of freedom.

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1966 with total page 1372 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1965 with total page 1916 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Epitaxial Growth of III Nitride Compounds written by Takashi Matsuoka and published by Springer. This book was released on 2018-04-17 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents extensive information on the mechanisms of epitaxial growth in III-nitride compounds, drawing on a state-of-the-art computational approach that combines ab initio calculations, empirical interatomic potentials, and Monte Carlo simulations to do so. It discusses important theoretical aspects of surface structures and elemental growth processes during the epitaxial growth of III-nitride compounds. In addition, it discusses advanced fundamental structural and electronic properties, surface structures, fundamental growth processes and novel behavior of thin films in III-nitride semiconductors. As such, it will appeal to all researchers, engineers and graduate students seeking detailed information on crystal growth and its application to III-nitride compounds.

Download or read book Advanced Physics of Electron Transport in Semiconductors and Nanostructures written by Massimo V. Fischetti and published by Springer. This book was released on 2016-05-20 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook is aimed at second-year graduate students in Physics, Electrical Engineering, or Materials Science. It presents a rigorous introduction to electronic transport in solids, especially at the nanometer scale.Understanding electronic transport in solids requires some basic knowledge of Hamiltonian Classical Mechanics, Quantum Mechanics, Condensed Matter Theory, and Statistical Mechanics. Hence, this book discusses those sub-topics which are required to deal with electronic transport in a single, self-contained course. This will be useful for students who intend to work in academia or the nano/ micro-electronics industry.Further topics covered include: the theory of energy bands in crystals, of second quantization and elementary excitations in solids, of the dielectric properties of semiconductors with an emphasis on dielectric screening and coupled interfacial modes, of electron scattering with phonons, plasmons, electrons and photons, of the derivation of transport equations in semiconductors and semiconductor nanostructures somewhat at the quantum level, but mainly at the semi-classical level. The text presents examples relevant to current research, thus not only about Si, but also about III-V compound semiconductors, nanowires, graphene and graphene nanoribbons. In particular, the text gives major emphasis to plane-wave methods applied to the electronic structure of solids, both DFT and empirical pseudopotentials, always paying attention to their effects on electronic transport and its numerical treatment. The core of the text is electronic transport, with ample discussions of the transport equations derived both in the quantum picture (the Liouville-von Neumann equation) and semi-classically (the Boltzmann transport equation, BTE). An advanced chapter, Chapter 18, is strictly related to the ‘tricky’ transition from the time-reversible Liouville-von Neumann equation to the time-irreversible Green’s functions, to the density-matrix formalism and, classically, to the Boltzmann transport equation. Finally, several methods for solving the BTE are also reviewed, including the method of moments, iterative methods, direct matrix inversion, Cellular Automata and Monte Carlo. Four appendices complete the text.

Download or read book Theoretical and Computational Approaches to Interface Phenomena written by J.T. Golab and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many chemical processes that are important to society take place at boundaries between phases. Understanding these processes is critical in order for them to be subject to human control. The building of theoretical or computational models of them puts them into a theoretical framework in terms of which the behavior of the system can be understood on a detailed level. Theoretical and computational models are often capable of giving descriptions of interfacial phenomena that are more detailed, on a molecular level, than can be obtained through experimental observation. Advances in computer hardware have also made possible the treatment of larger and chemically more interesting systems. The study of interfacial phenomena is a multi-disciplinary endeavor which requires collaboration and communication among researchers in different fields and across different types of institutions. Because there are many important problems in this field much effort is being expended to understand these processes by industrial laboratories as well as by groups at universities. Our conference titled "Theoretical and Computational Approaches to Interface Phenomena" held at South Dakota State University, August 2-4, 1993 brought together over thirty scientists from industry and academia and three countries in the western hemisphere to discuss the modeling of interfacial phenomena.

Download or read book Chemical Synergies written by Nuno A.G. Bandeira and published by Walter de Gruyter GmbH & Co KG. This book was released on 2018-05-07 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives an overview of recent integrated and inter-disciplinary approaches between chemical experiment and theory in a variety of fields, from polymer science to materials chemistry and ranging from the design of tailored properties to catalysis and reactivity, building on the well-established success of Density Functional Theory as the foremost quantum chemical method to provide qualitative and quantitative interpretation of results from the chemical laboratory. The combination of several characterization techniques with an understanding at the molecular level of chemical and physical phenomena are the main focal point of the subject matter.

Download or read book 3D QSAR in Drug Design written by Hugo Kubinyi and published by Springer Science & Business Media. This book was released on 2006-04-11 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: Significant progress has been made in the study of three-dimensional quantitative structure-activity relationships (3D QSAR) since the first publication by Richard Cramer in 1988 and the first volume in the series. 3D QSAR in Drug Design. Theory, Methods and Applications, published in 1993. The aim of that early book was to contribute to the understanding and the further application of CoMFA and related approaches and to facilitate the appropriate use of these methods. Since then, hundreds of papers have appeared using the quickly developing techniques of both 3D QSAR and computational sciences to study a broad variety of biological problems. Again the editor(s) felt that the time had come to solicit reviews on published and new viewpoints to document the state of the art of 3D QSAR in its broadest definition and to provide visions of where new techniques will emerge or new appli- tions may be found. The intention is not only to highlight new ideas but also to show the shortcomings, inaccuracies, and abuses of the methods. We hope this book will enable others to separate trivial from visionary approaches and me-too methodology from in- vative techniques. These concerns guided our choice of contributors. To our delight, our call for papers elicited a great many manuscripts.

Download or read book Morphological Compositional and Shape Control of Materials for Catalysis written by Paolo Fornasiero and published by Elsevier. This book was released on 2017-05-23 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt: Morphological, Compositional, and Shape Control of Materials for Catalysis, Volume 177, the latest in the Studies in Surface Science and Catalysis series, documents the fast-growing developments in the synthesis, characterization, and utilization of nanostructures for catalysis. The book provides essential background on using well-defined materials for catalysis and presents exciting new paradigms in the preparation and application of catalytic materials, with an emphasis on how structure determines catalytic properties. In addition, the book uniquely features discussions on the future of the field, with ample space for future directions detailed in each chapter. Presents the latest paradigms in the preparation and application of catalytic materials Provides essential background on using well-defined materials for catalysis Features discussion of future directions at the end of each chapter

Download or read book Machine Learning in Molecular Sciences written by Chen Qu and published by Springer Nature. This book was released on 2023-11-02 with total page 323 pages. Available in PDF, EPUB and Kindle. Book excerpt: Machine learning and artificial intelligence have propelled research across various molecular science disciplines thanks to the rapid progress in computing hardware, algorithms, and data accumulation. This book presents recent machine learning applications in the broad research field of molecular sciences. Written by an international group of renowned experts, this edited volume covers both the machine learning methodologies and state-of-the-art machine learning applications in a wide range of topics in molecular sciences, from electronic structure theory to nuclear dynamics of small molecules, to the design and synthesis of large organic and biological molecules. This book is a valuable resource for researchers and students interested in applying machine learning in the research of molecular sciences.

Download or read book Nanoalloys written by Florent Calvo and published by Newnes. This book was released on 2013-03-12 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoalloys: From Fundamentals to Emergent Applications presents and discusses the major topics related to nanoalloys at a time when the literature on the subject remains scarce. Particular attention is paid to experimental and theoretical aspects under the form of broad reviews covering the most recent developments. The book is organized into 11 chapters covering the most fundamental aspects of nanoalloys related to their synthesis and characterization, as well as their theoretical study. Aspects related to their thermodynamics and kinetics are covered as well. The coverage then moves to more specific topics, including optics, magnetism and catalysis, and finally to biomedical applications and the technologically relevant issue of self-assembly. With no current single reference source on the subject, the work is invaluable for researchers as the nanoscience field moves swiftly to full monetization. Encapsulates physical science of structure, properties, size, composition and ordering at nanoscale, aiding synthesis of experimentation and modelling Multi-expert and interdisciplinary perspectives on growth, synthesis and characterization of bimetallic clusters and particulates supports expansion of your current research activity into applications Synthesizes concepts and draws links between fundamental metallurgy and cutting edge nanoscience, aiding interdisciplinary research activity

Download or read book Synthesis and characterization of magnetic nanolaminated carbides written by Andrejs Petruhins and published by Linköping University Electronic Press. This book was released on 2018-03-15 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: MAX phases are a group of nanolaminated ternary carbides and nitrides, with a composition expressed by the general formula Mn+1AXn (?? = 1 ? 3), where M is a transition metal, A is an A-group element, and X is carbon and/or nitrogen. MAX phases have attracted interest due to their unique combination of metallic and ceramic properties, related to their inherently laminated structure of a transition metal carbide (Mn+1Xn) layer interleaved by an A-group metal layer. This Thesis explores synthesis and characterization of magnetic MAX phases, where the A-group element is gallium (Ga). Due to the low melting point of Ga (T = 30 °C), conventional thin film synthesis methods become challenging, as the material is in liquid form at typical process temperatures. Development of existing methods has therefore been investigated, for reliable/reproducible synthesis routes, including sputtering from a liquid target, and resulting high quality material. Routes for minimizing trial-and-error procedures during optimization of thin film synthesis have also been studied, allowing faster identification of optimal deposition conditions and a simplified transfer of essential deposition parameters between different deposition systems. A large part of this Thesis is devoted towards synthesis of MAX phase thin films in the Cr-Mn-Ga-C system. First, through process development, thin films of Cr2GaC were deposited by magnetron sputtering. The films were epitaxial, however with small amount of impurity phase Cr3Ga, as confirmed by X-ray diffraction (XRD) measurements. The film structure was confirmed by scanning transmission electron microscopy (STEM) and the composition by energy dispersive X-ray spectroscopy (EDX) inside the TEM. Inspired by predictive ab initio calculations, the new MAX phase Mn2GaC was successfully synthesized in thin film form by magnetron sputtering. Structural parameters and magnetic properties were analysed. The material was found to have two magnetic transitions in the temperature range 3 K to 750 K, with a first order transition at around 214 K, going from non-collinear antiferromagnetic state at lower temperature to an antiferromagnetic state at higher temperature. The Neél temperature was determined to be 507 K, changing from an antiferromagnetic to a paramagnetic state. Above 800 K, Mn2GaC decomposes. Furthermore, magnetostrictive, magnetoresistive and magnetocaloric properties of the material were iv determined, among which a drastic change in lattice parameters upon the first magnetic transition was observed. This may be of interest for magnetocaloric applications. Synthesis of both Cr2GaC and Mn2GaC in thin film form opens the possibility to tune the magnetic properties through a solid solution on the transition metal site, by alloying the aforementioned Cr2GaC with Mn, realizing (Cr1-xMnx)2GaC. From a compound target with a Cr:Mn ratio of 1:1, thin films of (Cr0.5Mn0.5)2GaC were synthesized, confirmed by TEM-EDX. Optimized structure was obtained by deposition on MgO substrates at a deposition temperature of 600 ºC. The thin films were phase pure and of high structural quality, allowing magnetic measurements. Using vibrating sample magnetometry (VSM), it was found that (Cr0.5Mn0.5)2GaC has a ferromagnetic component in the temperature range from 30 K to 300 K, with the measured magnetic moment at high field decreasing by increasing temperature. The remanent moment and coercive field is small, 0.036 ?B, and 12 mT at 30 K, respectively. Using ferromagnetic resonance spectroscopy, it was also found that the material has pure spin magnetism, as indicated by the determined spectroscopic splitting factor g = 2.00 and a negligible magnetocrystalline anisotropy energy. Fuelled by the recent discoveries of in-plane chemically ordered quaternary MAX phases, so called i-MAX phases, and guided by ab initio calculations, new members within this family, based on Cr and Mn, were synthesized by pressureless sintering methods, realizing (Cr2/3Sc1/3)2GaC and (Mn2/3Sc1/3)2GaC. Their structural properties were determined. Through these phases, the Mn content is the highest obtained in a bulk MAX phase to date. This work has further developed synthesis processes for sputtering from liquid material, for an optimized route to achieve thin films of controlled composition and a high structural quality. Furthermore, through this work, Mn has been added as a new element in the family of MAX phase elements. It has also been shown, that alloying with different content of Mn gives rise to varying magnetic properties in MAX phases. As a result of this Thesis, it is expected that the MAX phase family can be further expanded, with more members of new compositions and new properties.

Download or read book Introductory Quantum Mechanics with MATLAB written by James R. Chelikowsky and published by John Wiley & Sons. This book was released on 2019-01-04 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents a unique approach to grasping the concepts of quantum theory with a focus on atoms, clusters, and crystals Quantum theory of atoms and molecules is vitally important in molecular physics, materials science, nanoscience, solid state physics and many related fields. Introductory Quantum Mechanics with MATLAB is designed to be an accessible guide to quantum theory and its applications. The textbook uses the popular MATLAB programming language for the analytical and numerical solution of quantum mechanical problems, with a particular focus on clusters and assemblies of atoms. The textbook is written by a noted researcher and expert on the topic who introduces density functional theory, variational calculus and other practice-proven methods for the solution of quantum-mechanical problems. This important guide: -Presents the material in a didactical manner to help students grasp the concepts and applications of quantum theory -Covers a wealth of cutting-edge topics such as clusters, nanocrystals, transitions and organic molecules -Offers MATLAB codes to solve real-life quantum mechanical problems Written for master's and PhD students in physics, chemistry, material science, and engineering sciences, Introductory Quantum Mechanics with MATLAB contains an accessible approach to understanding the concepts of quantum theory applied to atoms, clusters, and crystals.