Quantum Mechanical First Principles Calculations of the Electronic and Magnetic Structure of Fe-Bearing Rock-Forming Silicates PDF Download
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Author: Danylo Zherebetskyy Publisher: Universal-Publishers ISBN: 1599423162 Category : Science Languages : en Pages : 138
Book Description
The focus of this thesis is the study of the electronic and magnetic structure of three representative members of Fe-bearing rock-forming silicates, viz. orthoferrosilite (Fe2+2Si2O6), almandine (Fe2+3Al2(SiO4)3) and andradite (Ca3Fe3+2(SiO4)3). These minerals have attracted significant attention due to their abundance in the Earth's crust and mantle, and because crystallised silicates are main components of cosmic dust which is the most abundant raw material in the Universe. For this purpose quantum mechanical first principles electronic structure calculations are performed by the most efficient DFT method in the local spin-density approximation for calculating spectroscopic data: the spin-polarized self consistent charge Xa method. The specific feature and strength of these investigations consist in the theoretical characterization of these complex systems based on experimental results. This means that, on one hand, experimental spectroscopic and crystallographic data are being used to judge the reliability of the calculations, whereas, on the other hand, experimental data are interpreted and explained by the theoretical results. This work comprises seven chapters. After a brief introduction (Chapter 1) Chapter 2 describes the theoretical bases, ideas, approximations and advantages of the SCC- Xa method and basics of the art of cluster construction. Chapter 3 considers physical bases of crystal field theory, absorption, Mossbauer spectroscopy and magnetic interactions, as well as the calculation of spectroscopic data within the frame of the SCC-Xa method. In addition, tetragonally, trigonally and angularly distorted octahedral sites with various degrees of the distortions are calculated and analyzed. The electronic and magnetic structures of orthoferrosilite, almandine and andradite are described in the following chapters. In the case of orthoferrosilite the magnetic interactions between the iron spins within the ribbons and between neighboring ribbons are characterized. Two identical interpenetrating magnetic sublattices of circles of 10 edge-shared dodecahedra are revealed and characterized in almandine. The calculated spin structure explains and solves the controversy in the interpretation of the Mossbauer spectra of almandine below the Neel temperature. For andradite a model of the magnetic structure is proposed based on geometrical considerations and the calculated spin coupling constants for the various interaction pathways. According to this model, the magnetic structure of andradite consists of two frustrated equivalent magnetic sublattices. The spins of the Fe ions within each sublattice are coupled antiferromagnetically. The derived spin pattern explains two sextets in the Mossbauer spectra of andradite below the Neel temperature. Finally, the main results are summarized in Chapter 7.
Author: Danylo Zherebetskyy Publisher: Universal-Publishers ISBN: 1599423162 Category : Science Languages : en Pages : 138
Book Description
The focus of this thesis is the study of the electronic and magnetic structure of three representative members of Fe-bearing rock-forming silicates, viz. orthoferrosilite (Fe2+2Si2O6), almandine (Fe2+3Al2(SiO4)3) and andradite (Ca3Fe3+2(SiO4)3). These minerals have attracted significant attention due to their abundance in the Earth's crust and mantle, and because crystallised silicates are main components of cosmic dust which is the most abundant raw material in the Universe. For this purpose quantum mechanical first principles electronic structure calculations are performed by the most efficient DFT method in the local spin-density approximation for calculating spectroscopic data: the spin-polarized self consistent charge Xa method. The specific feature and strength of these investigations consist in the theoretical characterization of these complex systems based on experimental results. This means that, on one hand, experimental spectroscopic and crystallographic data are being used to judge the reliability of the calculations, whereas, on the other hand, experimental data are interpreted and explained by the theoretical results. This work comprises seven chapters. After a brief introduction (Chapter 1) Chapter 2 describes the theoretical bases, ideas, approximations and advantages of the SCC- Xa method and basics of the art of cluster construction. Chapter 3 considers physical bases of crystal field theory, absorption, Mossbauer spectroscopy and magnetic interactions, as well as the calculation of spectroscopic data within the frame of the SCC-Xa method. In addition, tetragonally, trigonally and angularly distorted octahedral sites with various degrees of the distortions are calculated and analyzed. The electronic and magnetic structures of orthoferrosilite, almandine and andradite are described in the following chapters. In the case of orthoferrosilite the magnetic interactions between the iron spins within the ribbons and between neighboring ribbons are characterized. Two identical interpenetrating magnetic sublattices of circles of 10 edge-shared dodecahedra are revealed and characterized in almandine. The calculated spin structure explains and solves the controversy in the interpretation of the Mossbauer spectra of almandine below the Neel temperature. For andradite a model of the magnetic structure is proposed based on geometrical considerations and the calculated spin coupling constants for the various interaction pathways. According to this model, the magnetic structure of andradite consists of two frustrated equivalent magnetic sublattices. The spins of the Fe ions within each sublattice are coupled antiferromagnetically. The derived spin pattern explains two sextets in the Mossbauer spectra of andradite below the Neel temperature. Finally, the main results are summarized in Chapter 7.
Author: Werner Lottermoser Publisher: CRC Press ISBN: 1351767666 Category : Science Languages : en Pages : 158
Book Description
This book deals with the difference electron nanoscope (DEN), whose principles have been invented and realised by the book author. The DEN is based on a smart combination of diffractometric and spectroscopic data and uses a visualisation of three-dimensional difference electron densities (in our case stemming from 3d orbitals) in order to obtain the key quantity involved, the electric field gradient (efg). However, the DEN is no machine, as the title of the book might infer. It is a computer program running on a fast computer system displaying 3D difference electron hyperareas floating in space and the relevant efg as a wire frame model within the unit cell of the sample involved. In this sense, it acts on a sub-nanometer scale (hence the term "nanoscope") and generates images of uncompared symmetrical and physical evidence—and beauty. For the first time, diffractometry and spectroscopy have been integrated for the common synergetic effects that may contribute to a better understanding of electric and magnetic interactions in a crystal. The experimental derivation of the common quantity, the efg, is not confined to iron-containing samples, as the use of Mössbauer spectroscopy might infer, but can also be determined by nuclear quadrupole resonance that is not confined to special nuclides. Hence, the DEN can be applied to a huge multitude of scientifically interesting specimens since the main method involved, diffractometry in a wide sense, has no general limitations at all. So it is a rather universal method, and the monograph might contribute to a wide distribution of the method in the scientific world. Has anyone seen a real orbital before: a real orbital distribution in a crystal unit cell together with its efg tensor ellipsoid? In this book, one can see it.
Author: R W Grimes Publisher: World Scientific ISBN: 9814506044 Category : Science Languages : en Pages : 480
Book Description
This review volume takes an indepth look at the current research done in this important area of solid state science. Although the emphasis is on modelling the properties of definite materials, perfect crystal lattices are also considered in some detail. It is noteworthy that the review articles are written by some of the best known experts in the field. Contents:Hartree-Fock Method in Solid State Theory (I V Aberenkov & I M Antanova)The Green Function Method Used for Modelling the Scanning Tunnel Microscope (V L Bulatov & A K Kazansky)Adsorption and Reactions at Surfaces (E A Colbourn)How to Tell a Defect About the BulkA Survey of Embedding Methods (A J Fisher)Theory of Defects and Defect Processes in Silicon Dioxide and the Silicon-Silicon Dioxide Interface (W B Fowler)Anionic Polarizability in Halides and Chalcogenides (P W Fowler & P Tole)Models of Self-Trapped Excitons in Insulating Solids (A L Shluger et al.)On the Calculation of Defect Gibbs Energies For Ionic Crystals (P W M Jacobs)Short-Range Polarization in Insulators (G D Mahan)Ab-Initio Hartree-Fock Perturbed-Cluster Treatment of Local Defects in Crystals: Application to Carbon Impurities in Silicon (C Pisani et al.)Nonlinear Optical Constants in Alkali Halide Crystals (K R Subbaswamy)A Theory of Scanning Tunneling Microscopy and Spectroscopy Based on the Local Density Functional Approach (M Tsukada et al.)Embedded Quantum Cluster Simulation of Point Defects and Electronic Band Structures of Ionic Crystals (J M Vail et al.)and other papers Readership: Solid state chemists, physicists and materials scientists. keywords:Quantum Mechanical;Solid State;Atomic Scale Simulations;Defect Processes;Embedded Clusters;Electron Levels;Electronic Structure;Local Density Functional;Hartree-Fock;Excited States;Clusters;Defects;Surfaces;Diffusion;Spectroscopy;Impurities
Author: Lisa Tauxe Publisher: Univ of California Press ISBN: 0520260317 Category : Science Languages : en Pages : 505
Book Description
"This book by Lisa Tauxe and others is a marvelous tool for education and research in Paleomagnetism. Many students in the U.S. and around the world will welcome this publication, which was previously only available via the Internet. Professor Tauxe has performed a service for teaching and research that is utterly unique."—Neil D. Opdyke, University of Florida
Author: Vasudevan Ramesh Publisher: Royal Society of Chemistry ISBN: 1782620532 Category : Nuclear magnetic resonance Languages : en Pages : 326
Book Description
This volume will focus on a theme - NMR applications in industry and providing a comprehensive yet critical review of the current literature from various industries.
Author: Liyuan Liang Publisher: Springer Science & Business Media ISBN: 0387094164 Category : Technology & Engineering Languages : en Pages : 641
Book Description
Neutron Applications in Earth, Energy and Environmental Sciences offers a comprehensive overview of the wide ranging applications of neutron scattering techniques to elucidate the fundamental materials properties at the nano-, micro- and meso-scale, which underpin research in the related fields of Earth, Energy and Environmental Sciences. Introductions to neutron scattering fundamentals and instrumentation are paired with a thorough review of the applications to a large variety of scientific and technological problems, written through the direct experience of leading scientists in each field. Tailored to a wide audience, this volume provides the novice with an inspiring introduction and stimulates the expert to consider these non-conventional problem solving techniques in his/her field of interest. Earth and environmental scientists, engineers, researchers and graduate students involved with materials science will find Neutron Applications in Earth, Energy and Environmental Sciences a valuable ready-to-use reference.
Author: Danylo Zherebetskyy
Author: Danylo Zherebetskyy
Author: Werner Lottermoser
Author: R W Grimes
Author: 
Author: Lisa Tauxe
Author: Vasudevan Ramesh
Author: Janice L. Bishop
Author: Bonnie J. McBride
Author: Liyuan Liang
Author: Lorin Rollins Stieff