Theoretical Prediction Of Properties Of Atomistic Systems
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Theoretical Prediction Of Properties Of Atomistic Systems
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Author : Alexander Lindmaa
language : en
Publisher: Linköping University Electronic Press
Release Date : 2017-08-15
Theoretical Prediction Of Properties Of Atomistic Systems written by Alexander Lindmaa and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-08-15 with categories.
The prediction of ground state properties of atomistic systems is of vital importance in technological advances as well as in the physical sciences. Fundamentally, these predictions are based on a quantum-mechanical description of many-electron systems. One of the hitherto most prominent theories for the treatment of such systems is density functional theory (DFT). The main reason for its success is due to its balance of acceptable accuracy with computational efficiency. By now, DFT is applied routinely to compute the properties of atomic, molecular, and solid state systems. The general approach to solve the DFT equations is to use a density-functional approximation (DFA). In Kohn-Sham (KS) DFT, DFAs are applied to the unknown exchangecorrelation (xc) energy. In orbital-free DFT on the other hand, where the total energy is minimized directly with respect to the electron density, a DFA applied to the noninteracting kinetic energy is also required. Unfortunately, central DFAs in DFT fail to qualitatively capture many important aspects of electronic systems. Two prime examples are the description of localized electrons, and the description of systems where electronic edges are present. In this thesis, I use a model system approach to construct a DFA for the electron localization function (ELF). The very same approach is also taken to study the non-interacting kinetic energy density (KED) in the slowly varying limit of inhomogeneous electron densities, where the effect of electronic edges are effectively included. Apart from the work on model systems, extensions of an exchange energy functional with an improved KS orbital description are presented: a scheme for improving its description of energetics of solids, and a comparison of its description of an essential exact exchange feature known as the derivative discontinuity with numerical data for exact exchange. An emerging alternative route towards the prediction of the properties of atomistic systems is machine learning (ML). I present a number of ML methods for the prediction of solid formation energies, with an accuracy that is on par with KS DFT calculations, and with orders-of-magnitude lower computational cost. Att kunna förutsäga egenskaper hos atomistiska system utgör en viktigdel av vår teknologiska utveckling, samt spelar en betydande roll i defysikaliska vetenskaperna. Sådana förutsägelser bygger på en kvantmekaniskbeskrivning av mångelektronsystem. En av de mest framståendeteorierna för att behandla den här typen av system är täthetsfunktionalteorin(DFT). Den främsta orsaken till dess framgång är attden lyckas kombinera skaplig noggrannhet med en bra beräkningseffektivitet.DFT används numera rutinmässigt för att beräkna storheterhos atomer, molekyler, och fasta kroppar. Generellt sett löses ekvationerna inom DFT genom att man inför entäthetsfunktionalapproximation (DFA). I Kohn-Sham (KS) DFT, användsDFAer för att approximera utbytes-korrelationsenergin. Inom orbitalfriDFT, där målet är att direkt minimera den totala energin med avseendepå elektrontätheten, så approximerar man också den icke-interageranderörelseenergin hos elektronerna. Dessvärre så fallerar många centralaDFAer att kvalitativt beskriva många viktiga aspekter hos elektronsystem.Två viktiga exempel är beskrivningen av lokaliserade elektroner,samt beskrivningen av system där det förekommer elektronytor. I denna avhandling använder jag modellsystem för att konstruera enDFAför elektronlokaliseringsfunktionen (ELF). Samma tillvägagångssättappliceras sedan för att studera den kinetiska energitätheten i gränsen avlångsamt varierande elektrontätheter, där effekten av elektronytor effektivtinkluderas. Förutom arbetet som berör modellsystem, så presenterasen utökad variant av en utbytes-energifunktional med en förbättrad KSorbitalbeskrivning: ett schema för att förbättra dess energiegenskaperför solida material, samt en jämförelse av dess beskrivning av en viktigegenskap hos den exakta utbytesenergin, vilket utgörs av diskontinuiteteri dess derivata. Ett mera nyligen uppkommet samt alternativt sätt att kunna förutsägaegenskaper hos atomistiska system utgörs av maskinlärning (ML).Jag presenterar ett antal ML-modeller för att kunna förutsäga formeringsenergierhos fasta material med en noggrannhet som är i linje medresultat som uppnås av beräkningar med hjälp av KS DFT, och med enberäkningseffektivitet som är flera storleksordningar snabbare.
Electrocatalysis
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Author : Richard C. Alkire
language : en
Publisher: John Wiley & Sons
Release Date : 2013-12-16
Electrocatalysis written by Richard C. Alkire and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-12-16 with Science categories.
Catalysts speed up a chemical reaction or allow for reactions to take place that would not otherwise occur. The chemical nature of a catalyst and its structure are crucial for interactions with reaction intermediates. An electrocatalyst is used in an electrochemical reaction, for example in a fuel cell to produce electricity. In this case, reaction rates are also dependent on the electrode potential and the structure of the electrical double-layer. This work provides a valuable overview of this rapidly developing field by focusing on the aspects that drive the research of today and tomorrow. Key topics are discussed by leading experts, making this book a must-have for many scientists of the field with backgrounds in different disciplines, including chemistry, physics, biochemistry, engineering as well as surface and materials science. This book is volume XIV in the series "Advances in Electrochemical Sciences and Engineering".
Optimised Projections For The Ab Initio Simulation Of Large And Strongly Correlated Systems
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Author : David D. O'Regan
language : en
Publisher: Springer Science & Business Media
Release Date : 2011-09-24
Optimised Projections For The Ab Initio Simulation Of Large And Strongly Correlated Systems written by David D. O'Regan and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-09-24 with Technology & Engineering categories.
Density functional theory (DFT) has become the standard workhorse for quantum mechanical simulations as it offers a good compromise between accuracy and computational cost. However, there are many important systems for which DFT performs very poorly, most notably strongly-correlated materials, resulting in a significant recent growth in interest in 'beyond DFT' methods. The widely used DFT+U technique, in particular, involves the addition of explicit Coulomb repulsion terms to reproduce the physics of spatially-localised electronic subspaces. The magnitude of these corrective terms, measured by the famous Hubbard U parameter, has received much attention but less so for the projections used to delineate these subspaces. The dependence on the choice of these projections is studied in detail here and a method to overcome this ambiguity in DFT+U, by self-consistently determining the projections, is introduced. The author shows how nonorthogonal representations for electronic states may be used to construct these projections and, furthermore, how DFT+U may be implemented with a linearly increasing cost with respect to system size. The use of nonorthogonal functions in the context of electronic structure calculations is extensively discussed and clarified, with new interpretations and results, and, on this topic, this work may serve as a reference for future workers in the field.
Theoretical And Computational Methods In Mineral Physics
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Author : Renata M. Wentzcovitch
language : en
Publisher: Walter de Gruyter GmbH & Co KG
Release Date : 2018-12-17
Theoretical And Computational Methods In Mineral Physics written by Renata M. Wentzcovitch and has been published by Walter de Gruyter GmbH & Co KG this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-12-17 with Science categories.
Volume 71 of Reviews in Mineralogy and Geochemistry represents an extensive review of the material presented by the invited speakers at a short course on Theoretical and Computational Methods in Mineral Physics held prior (December 10-12, 2009) to the Annual fall meeting of the American Geophysical Union in San Francisco, California. The meeting was held at the Doubletree Hotel & Executive Meeting Center in Berkeley, California. Contents: Density functional theory of electronic structure: a short course for mineralogists and geophysicists The Minnesota density functionals and their applications to problems in mineralogy and geochemistry Density-functional perturbation theory for quasi-harmonic calculations Thermodynamic properties and phase relations in mantle minerals investigated by first principles quasiharmonic theory First principles quasiharmonic thermoelasticity of mantle minerals An overview of quantum Monte Carlo methods Quantum Monte Carlo studies of transition metal oxides Accurate and efficient calculations on strongly correlated minerals with the LDA+U method: review and perspectives Spin-state crossover of iron in lower-mantle minerals: results of DFT+U investigations Simulating diffusion Modeling dislocations and plasticity of deep earth materials Theoretical methods for calculating the lattice thermal conductivity of minerals Evolutionary crystal structure prediction as a method for the discovery of minerals and materials Multi-Mbar phase transitions in minerals Computer simulations on phase transitions in ice Iron at Earth’s core conditions from first principles calculations First-principles molecular dynamics simulations of silicate melts: structural and dynamical properties Lattice dynamics from force-fields as a technique for mineral physics An efficient cluster expansion method for binary solid solutions: application to the halite-silvite, NaCl-KCl, system Large scale simulations Thermodynamics of the Earth’s mantle
Renormalization Group Theory
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Author : Ulrich Köbler
language : en
Publisher: Springer Science & Business Media
Release Date : 2010-04-29
Renormalization Group Theory written by Ulrich Köbler and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010-04-29 with Technology & Engineering categories.
Spin wave theory of magnetism and BCS theory of superconductivity are typical theories of the time before renormalization group (RG) theory. The two theories consider atomistic interactions only and ignore the energy degrees of freedom of the continuous (infinite) solid. Since the pioneering work of Kenneth G. Wilson (Nobel Prize of physics in 1982) we know that the continuous solid is characterized by a particular symmetry: invariance with respect to transformations of the length scale. Associated with this symmetry are particular field particles with characteristic excitation spectra. In diamagnetic solids these are the well known Debye bosons. This book reviews experimental work on solid state physics of the last five decades and shows in a phenomenological way that the dynamics of ordered magnets and conventional superconductors is controlled by the field particles of the infinite solid and not by magnons and Cooper pairs, respectively. In the case of ordered magnets the relevant field particles are called GSW bosons after Goldstone, Salam and Weinberg and in the case of superconductors the relevant field particles are called SC bosons. One can imagine these bosons as magnetic density waves or charge density waves, respectively. Crossover from atomistic exchange interactions to the excitations of the infinite solid occurs because the GSW bosons have generally lower excitation energies than the atomistic magnons. According to the principle of relevance the dynamics is governed by the excitations with the lowest energy. The non relevant atomistic interactions with higher energy are practically unimportant for the dynamics.
Monte Carlo And Molecular Dynamics Simulations In Polymer Science
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Author : Kurt Binder
language : en
Publisher: Oxford University Press
Release Date : 1995-08-03
Monte Carlo And Molecular Dynamics Simulations In Polymer Science written by Kurt Binder and has been published by Oxford University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995-08-03 with Science categories.
Written by leading experts from around the world, Monte Carlo and Molecular Dynamics Simulations in Polymer Science comprehensively reviews the latest simulation techniques for macromolecular materials. Focusing in particular on numerous new techniques, the book offers authoritative introductions to solutions of neutral polymers and polyelectrolytes; dynamics of polymer melts, rubbers and gels, and glassy materials; thermodynamics of polymer mixing and mesophase formation, and polymers confined at interfaces and grafted to walls. Throughout, contributors offer practical advice on how to overcome the unique challenges posed by the large size and slow relaxation of polymer coils. Students and researchers in polymer chemistry, polymer physics, chemical engineering, and materials and computational science will all benefit from the cogent, step-by-step introductions contained in this important new book.
Molecular Simulation Fracture Gel Theory
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Author :
language : en
Publisher: Springer
Release Date : 2003-07-03
Molecular Simulation Fracture Gel Theory written by and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003-07-03 with Technology & Engineering categories.
Free Boundary Problems Theory And Applications
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Author : Marek Niezgodka
language : en
Publisher: CRC Press
Release Date : 1996-11-25
Free Boundary Problems Theory And Applications written by Marek Niezgodka and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996-11-25 with Mathematics categories.
Addressing various aspects of nonlinear partial differential equations, this volume contains papers and lectures presented at the Congress on Free boundary Problems, Theory and Application held in Zakopane, Poland in 1995. Topics include existence, uniqueness, asymptotic behavior, and regularity of solutions and interfaces.
Engineering Of Nanobiomaterials
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Author : Alexandru Grumezescu
language : en
Publisher: William Andrew
Release Date : 2016-01-14
Engineering Of Nanobiomaterials written by Alexandru Grumezescu and has been published by William Andrew this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-01-14 with Science categories.
Engineering of Nanobiomaterials presents the most recent information regarding the specific modifications of nanomaterials and of their synthesis methods, in order to obtain particular structures for different biomedical purposes. This book enables the results of current research to reach those who wish to use this knowledge in an applied setting. Engineered nanobiomaterials, designed from organic or inorganic raw materials, offer promising alternatives in many biomedical applications. In this book, eminent researchers from around the world discuss the various applications, including antibacterial therapy, biosensors, cancer therapy, stimuli-responsive drug release, drug delivery, gene therapy and visual prostheses. In each case, advantages, drawbacks and future potential are outlined. This book will be of interest to students, postdoctoral researchers and professors engaged in the fields of materials science, biotechnology and applied chemistry. It will also be highly valuable to those working in industry, including pharmaceutics and biotechnology companies, medical researchers, biomedical engineers and advanced clinicians. - An up-to-date and highly structured reference source for students, researchers and practitioners working in biomedical, biotechnological and engineering fields - A valuable guide to recent scientific progress, covering major and emerging applications of nanomaterials in the biomedical field - Proposes novel opportunities and ideas for developing or improving engineering technologies in nanomedicine/nanobiology
Proceedings Of The 12th Pacific Rim Conference On Ceramic And Glass Technology
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Author : Dileep Singh
language : en
Publisher: John Wiley & Sons
Release Date : 2018-04-19
Proceedings Of The 12th Pacific Rim Conference On Ceramic And Glass Technology written by Dileep Singh and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-04-19 with Technology & Engineering categories.
Ceramic Transactions, Volume 264, Proceedings of the 12th Pacific Rim Conference on Ceramic and Glass Technology Dileep Singh, Manabu Fukushima, Young-Wook Kim, Kiyoshi Shimamura, Nobuhito Imanaka, Tatsuki Ohji, Jake Amoroso, and Michael Lanagan; Editors This proceedings contains a collection of 32 papers presented at the 12th Pacific Rim Conference on Ceramic and Glass Technology (PacRim12), May 21-26, 2017 in Waikoloa, Hawaii. PacRim is a bi-annual conference held in collaboration with the ceramic societies of the Pacific Rim countries - The American Ceramic Society, The Chinese Ceramic Society, The Korean Ceramic Society, and the Australian Ceramic Society. Topics included in this collection include multiscale modeling and simulation, processing and manufacturing, nanotechnology, multifunctional materials, ceramics for energy and the environment, biomedical materials, and more