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
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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
Get Book Here
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: 1351767674
Category : Science
Languages : en
Pages : 264
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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:
Publisher:
ISBN:
Category : Geodesy
Languages : en
Pages : 760
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Book Description
Author: Lisa Tauxe
Publisher: Univ of California Press
ISBN: 0520260317
Category : Science
Languages : en
Pages : 505
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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: Bonnie J. McBride
Publisher:
ISBN:
Category : Chemical equilibrium
Languages : en
Pages : 300
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Book Description
Author: Holger T Grahn
Publisher: World Scientific Publishing Company
ISBN: 9813105151
Category : Science
Languages : en
Pages : 203
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Book Description
This book covers the physics of semiconductors on an introductory level, assuming that the reader already has some knowledge of condensed matter physics. Crystal structure, band structure, carrier transport, phonons, scattering processes and optical properties are presented for typical semiconductors such as silicon, but III-V and II-VI compounds are also included. In view of the increasing importance of wide-gap semiconductors, the electronic and optical properties of these materials are dealt with too.
Author: Ian David Brown
Publisher:
ISBN: 0198508700
Category : Science
Languages : en
Pages : 289
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Book Description
This book describes the bond valence model, a description of acid-base bonding which is becoming increasingly popular particularly in fields such as materials science and mineralogy where solid state inorganic chemistry is important. Recent improvements in crystal structure determination have allowed the model to become more quantitative. Unlike other models of inorganic chemical bonding, the bond valence model is simple, intuitive, and predictive, and can be used for analysing crystal structures and the conceptual modelling of local as well as extended structures. This is the first book to explore in depth the theoretical basis of the model and to show how it can be applied to synthetic and solution chemistry. It emphasizes the separate roles of the constraints of chemistry and of three-dimensional space by analysing the chemistry of solids. Many applications of the model in physics, materials science, chemistry, mineralogy, soil science, surface science, and molecular biology are reviewed. The final chapter describes how the bond valence model relates to and represents a simplification of other models of inorganic chemical bonding.
Author: R.C. Newton
Publisher: Springer Science & Business Media
ISBN: 1461258715
Category : Science
Languages : en
Pages : 312
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Book Description
Today large numbers of geoscientists apply thermodynamic theory to solu tions of a variety of problems in earth and planetary sciences. For most problems in chemistry, the application of thermodynamics is direct and rewarding. Geoscientists, however, deal with complex inorganic and organic substances. The complexities in the nature of mineralogical substances arise due to their involved crystal structure and multicomponental character. As a result, thermochemical solutions of many geological-planetological problems should be attempted only with a clear understanding of the crystal-chemical and thermochemical character of each mineral. The subject of physical geochemistry deals with the elucidation and application of physico-chemical principles to geosciences. Thermodynamics of mineral phases and crystalline solutions form an integral part of it. Developments in mineralogic thermody namics in recent years have been very encouraging, but do not easily reach many geoscientists interested mainly in applications. This series is to provide geoscientists and planetary scientists with current information on the develop ments in thermodynamics of mineral systems, and also provide the active researcher in this rapidly developing field with a forum through which he can popularize the important conclusions of his work. In the first several volumes, we plan to publish original contributions (with an abundant supply of back ground material for the uninitiated reader) and thoughtful reviews from a number of researchers on mineralogic thermodynamics, on the application of thermochemistry to planetary phase equilibria (including meteorites), and on kinetics of geochemical reactions.
Author: Nikolai Bagdassarov
Publisher: Cambridge University Press
ISBN: 1108390196
Category : Science
Languages : en
Pages : 566
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Book Description
Rock physics encompasses practically all aspects of solid and fluid state physics. This book provides a unified presentation of the underlying physical principles of rock physics, covering elements of mineral physics, petrology and rock mechanics. After a short introduction on rocks and minerals, the subsequent chapters cover rock density, porosity, stress and strain relationships, permeability, poroelasticity, acoustics, conductivity, polarizability, magnetism, thermal properties and natural radioactivity. Each chapter includes problem sets and focus boxes with in-depth explanations of the physical and mathematical aspects of underlying processes. The book is also supplemented by online MATLAB exercises to help students apply their knowledge to numerically solve rock physics problems. Covering laboratory and field-based measurement methods, as well as theoretical models, this textbook is ideal for upper-level undergraduate and graduate courses in rock physics. It will also make a useful reference for researchers and professional scientists working in geoscience and petroleum engineering.
Author: Giorgio Torraca
Publisher:
ISBN: 9780982766828
Category : Architecture
Languages : en
Pages : 204
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Book Description
This book is based on Dr. Torraca's 2002 publication, Lezioni di scienza e tecnologia dei materiali per restauro dei monumenti. The English-language Lectures includes new and updated material. An excellent resource for architectural conservators, engineers, and conservation scientists.
