Download or read book Electronic Structure Methods for Complex Materials written by Wai-Yim Ching and published by OUP Oxford. This book was released on 2012-05-17 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: Density functional theory (DFT) has blossomed in the past few decades into a powerful tool that is used by experimentalists and theoreticians alike. This book highlights the extensive contributions that the DFT-based OLCAO method has made to progress in this field, and it demonstrates its competitiveness for performing ab initio calculations on large and complex models of practical systems. A brief historical account and introduction to the elements of the theory set the stage for discussions on semiconductors, insulators, crystalline metals and alloys, complex crystals, non-crystalline solids and liquids, microstructure containing systems and those containing impurities, defects, and surfaces, biomolecular systems, and the technique of ab initio core level spectroscopy calculation.

Download or read book Electronic Structure Methods for Complex Materials written by Wai-Yim Ching and published by Oxford University Press. This book was released on 2012-05-17 with total page 325 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book details the application of the OLCAO method for calculating the properties of solids from fundamental principles to a wide array of material systems. The method specializes in large and complex models and is able to compute a variety of useful properties including electronic, optical, and spectroscopic properties.

Download or read book Methods of Electronic Structure Theory written by Henry F. Schaefer and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt: These two volumes deal with the quantum theory of the electronic structure of molecules. Implicit in the term ab initio is the notion that approximate solutions of Schrödinger's equation are sought "from the beginning," i. e. , without recourse to experimental data. From a more pragmatic viewpoint, the distin guishing feature of ab initio theory is usually the fact that no approximations are involved in the evaluation of the required molecular integrals. Consistent with current activity in the field, the first of these two volumes contains chapters dealing with methods per se, while the second concerns the application of these methods to problems of chemical interest. In asense, the motivation for these volumes has been the spectacular recent success of ab initio theory in resolving important chemical questions. However, these applications have only become possible through the less visible but equally important efforts of those develop ing new theoretical and computational methods and models. Henry F Schaefer Vll Contents Contents of Volume 4 XIX Chapter 1. Gaussian Basis Sets for Molecular Calculations Thom. H. Dunning, Ir. and P. Ieffrey Hay 1. Introduction . . . . . . . . . . . . . . . . 1 1. 1. Slater Functions and the Hydrogen Moleeule 1 1. 2. Gaussian Functions and the Hydrogen Atom 3 2. Hartree-Fock Calculations on the First Row Atoms 5 2. 1. Valence States of the First Row Atoms 6 7 2. 2. Rydberg States of the First Row Atoms 9 2. 3.

Download or read book Semiempirical Methods of Electronic Structure Calculation written by Gerald Segal and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 319 pages. Available in PDF, EPUB and Kindle. Book excerpt: If one reflects upon the range of chemical problems accessible to the current quantum theoretical methods for calculations on the electronic structure of molecules, one is immediately struck by the rather narrow limits imposed by economic and numerical feasibility. Most of the systems with which experimental photochemists actually work are beyond the grasp of ab initio methods due to the presence of a few reasonably large aromatic ring systems. Potential energy surfaces for all but the smallest molecules are extremely expensive to produce, even over a restricted group of the possible degrees of freedom, and molecules containing the higher elements of the periodic table remain virtually untouched due to the large numbers of electrons involved. Almost the entire class of molecules of real biological interest is simply out of the question. In general, the theoretician is reduced to model systems of variable appositeness in most of these fields. The fundamental problem, from a basic computational point of view, is that large molecules require large numbers of basis functions, whether Slater type orbitals or Gaussian functions suitably contracted, to provide even a modestly accurate description of the molecular electronic environment. This leads to the necessity of dealing with very large matrices and numbers of integrals within the Hartree-Fock approximation and quickly becomes both numerically difficult and uneconomic.

Download or read book Electronic States of Molecules and Atom Clusters written by G. Del Re and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Semiempirical Methods of Electronic Structure Calculation written by Gerald Segal and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt: If one reflects upon the range of chemical problems accessible to the current quantum theoretical methods for calculations on the electronic structure of molecules, one is immediately struck by the rather narrow limits imposed by economic and numerical feasibility. Most of the systems with which experimental photochemists actually work are beyond the grasp of ab initio methods due to the presence of a few reasonably large aromatic ring systems. Potential energy surfaces for all but the smallest molecules are extremely expensive to produce, even over a restricted group of the possible degrees of freedom, and molecules containing the higher elements of the periodic table remain virtually untouched due to the large numbers of electrons involved. Almost the entire class of molecules of real biological interest is simply out of the question. In general, the theoretician is reduced to model systems of variable appositeness in most of these fields. The fundamental problem, from a basic computational point of view, is that large molecules require large numbers of basis functions, whether Slater type orbitals or Gaussian functions suitably contracted, to provide even a modestly accurate description of the molecular electronic environment. This leads to the necessity of dealing with very large matrices and numbers of integrals within the Hartree-Fock approximation and quickly becomes both numerically difficult and uneconomic.

Download or read book Applications of Electronic Structure Theory written by Henry Schaefer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: These two volumes deal with the quantum theory of the electronic structure of ab initio is the notion that approximate solutions molecules. Implicit in the term of Schrodinger's equation are sought "from the beginning," i. e. , without recourse to experimental data. From a more pragmatic viewpoint, the distin guishing feature of ab initio theory is usually the fact that no approximations are involved in the evaluation of the required molecular integrals. Consistent with current activity in the field, the first of these two volumes contains chapters dealing with methods per se, while the second concerns the application of these methods to problems of chemical interest. In a sense, the motivation for these volumes has been the spectacular recent success of ab initio theory in resolving important chemical questions. However, these applications have only become possible through the less visible but equally important efforts of those developing new theoretical and computational methods and models. Henry F. Schaefer vii Contents Contents of Volume 3 xv Chapter 1. A Priori Geometry Predictions 1. A. Pople 1. Introduction . . . . . . . . . . . . . . . . . . . 1 2. Equilibrium Geometries by Hartree-Fock Theory 2 2. 1. Restricted and Unrestricted Hartree-Fock Theories 2 2. 2. Basis Sets for Hartree-Fock Studies . . . . . 4 2. 3. Hartree-Fock Structures for Small Molecules . 6 2. 4. Hartree-Fock Structures for Larger Molecules 12 3. Equilibrium Geometries with Correlation . . 18 4. Predictive Structures for Radicals and Cations 20 5. Conclusions 23 References 24 Chapter 2. Barriers to Rotation and Inversion Philip W. Payne and Leland C.

Download or read book Electronic Structure of Solids written by John Clarke Slater and published by . This book was released on 1953 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structures and Approximations for Electrons in Molecules written by David B. Cook and published by Ellis Horwood. This book was released on 1978 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modern Electronic Structure Theory written by D R Yarkony and published by World Scientific. This book was released on 1995-09-28 with total page 1552 pages. Available in PDF, EPUB and Kindle. Book excerpt: 0Keywords:“This treatise is a pedogogically oriented collection of 22 chapters chosen to comprehensively present the quantum mechanics of electronic phenomena in molecules. It is an excellent effort to match increases in the physical understanding of chemistry with the astonishing advances in digital computer power and accessibility … The two-volume set is a necessary addition to chemistry libraries or research group holdings.”J. Am. Chem. Soc.

Download or read book Electronic Structure of Materials written by Adrian P. Sutton and published by Clarendon Press. This book was released on 1993-09-30 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the modern real-space approach to electronic structures and properties of crystalline and non-crystalline materials in a form readily accessible to undergraduates in materials science, physics, and chemistry. - ;This book describes the modern real-space approach to electronic structures and properties of crystalline and non-crystalline materials in a form readily accessible to undergraduates in materials science, physics, and chemistry. -

Download or read book Electronic Structure of Atoms and Molecules written by Douglas Henderson and published by . This book was released on 1969 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Exploring Chemistry with Electronic Structure Methods written by James B. Foresman and published by . This book was released on 1996 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modern Electronic Structure Theory written by David Yarkony and published by World Scientific. This book was released on 1995 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern Electronic Structure Theory provides a didactically oriented description of the latest computational techniques in electronic structure theory and their impact in several areas of chemistry. The book is aimed at first year graduate students or college seniors considering graduate study in computational chemistry, or researchers who wish to acquire a wider knowledge of this field.

Download or read book One Dimensional Organometallic Materials written by Michael C. Böhm and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: This lecture note gives an analysis of electronic structure effects for a new class of molecular solids, i. e. one-dimensional organometal lic systems formed by transition-met. l atoms that are embedded in a matrix of macrocyclic organic ligands. These systems as well as orga nic metals have focused considerable interest due to the potential formation of high-mobility charge carriers. For the present author it is difficult to participate in this restriction on a single physical property (i. e. high electronic conductivities, technical applications, etc. ). The lecture note is hopefully a small contribution to enhance the general understanding of certain electronic properties in organo metallic polymers. Those problems have been considered in the first place that seem to form a theoretical deficit in one specific field of solid-state chemistry. For the reader it will become evident that this contribution is a compromise always guided and limited by boundaries: i) An attempt to present problems to a ·chemical· audience which have their roots in solid-state physics. ii) The model calculations are limited by the currently available computational facilities. This ·boundary· implies that the compu tational data a~e subject to severe theoretical approximations. iii) Theorists have often a strong tendency to identify their numeri cal results and models with physical effects. Also this lecture note is not free of this almost universal trend. Nevertheless the author hopes that this text leads to some insight into a rather modern research field. M. e. B6hm I.

Download or read book Electronic Structure Crystallography and Functional Motifs of Materials written by Guo-Cong Guo and published by John Wiley & Sons. This book was released on 2023-01-08 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electronic Structure Crystallography and Functional Motifs of Materials Detailed resource on the method of electronic structure crystallography for revealing the experimental electronic structure and structure-property relationships of functional materials Electronic Structure Crystallography and Functional Motifs of Materials describes electronic structure crystallography and functional motifs of materials, two of the most challenging topics to realize the rational design of high-performance functional materials, emphasizing the physical properties and structure-property relationships of functional materials using nonlinear optical materials as examples. The text clearly illustrates how to extract experimental electronic structure information and relevant physicochemical properties of materials based on the theories and methods in X-ray crystallography and quantum chemistry. Practical skills of charge density studies using experimental X-ray sources are also covered, which are particularly important for the future popularization and development of electron structure crystallography. This book also introduces the related theories and refinement techniques involved in using scattering methods (mainly X-ray single-crystal diffraction, as well as polarized neutron scattering and Compton scattering) to determine experimental electronic structures, including the experimental electron density, experimental electron wavefunction, and experimental electron density matrix of crystalline materials. Electronic Structure Crystallography and Functional Motifs of Materials includes information on: Basic framework and assumptions of the first-principle calculations, density matrix and density function, and Hartree-Fock (HF) and Kohn-Sham (KS) methods Analysis of topological atoms in molecules, chemical interaction analysis, coarse graining and energy partition of the density matrix, and restricted space partition Principles of electronic structure measurement, including thermal vibration analysis, scattering experiments, and refinement algorithm for experimental electronic structure Independent atom model, multipole model, X-ray constrained wavefunction model, and other electron density models Electronic Structure Crystallography and Functional Motifs of Materials is an ideal textbook or reference book for graduate students and researchers in chemistry, physics, and material sciences for studying the structures and properties of functional crystalline materials.

Download or read book Electronic transitions and correlation effects written by Johan Jönsson and published by Linköping University Electronic Press. This book was released on 2020-03-17 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: Macroscopic properties of real materials, such as conductivity, magneticproperties, crystal structure parameters, etc. are closely related or evendetermined by the configuration of their electrons, characterized by electronicstructure. By changing the conditions, e.g, pressure, temperature, magnetic/electric field, chemical doping, etc. one can modify the electronic structure ofsolids and therefore induce a phase transition(s) between different electronic andmagnetic states. One famous example is a Mott metal-to-insulator phase transition,at which a material undergoes a significant, often many orders of magnitude, changeof conductivity caused by the interplay between itineracy and localization of thecarriers. Electronic topological transitions (ETT) involvechanges in the topology of a metal's Fermi surface. This thesis investigates theeffect of such electronic transitions in various materials, ranging from pureelements to complex compounds. To describe the interplay between electronic transitionsand properties of real materials,different state-of-the-art computational methods are used. The densityfunctional theory(DFT), as well as the DFT + U method, is used to calculatestructural properties. The validity of recently introduced exchange-correlationfunctionals, such as the strongly constrained and appropriately normed (SCAN)functional, is also assessed for magnetic elements. In order toinclude dynamical effects of electron interactions we use the DFT + dynamical meanfield theory (DFT + DMFT) method. Experiments in hcp-Os have reported peculiarities in the ratio betweenlattice parameters at high pressure. Previous calculations have suggested these transitions maybe related to ETTs and even crossings of core levels at ultra high pressure. Inthis thesis it is shownthat the crossing of core levels is a general feature of heavy transitionmetals. Experiments have therefore been performed to look for indications ofthis transition in Ir using X-ray absorption spectroscopy. In NiO, strongrepulsion between electrons leads to a Mott insulating state at ambientconditions. It has long been predicted that high pressure will lead to aninsulator-to-metal transition. This has been suggested to be accompanied by aloss of magnetic order, and a structural phase transition. In collaboration withexperimentalists we look for thistransition by investigating the X-ray absorption spectra as well as themagnetic hyperfine field. We find no evidence of a Mott transition up to 280GPa. In the Mott insulator TiPO4, application of external pressure has beensuggested to lead to a spin-Peierls transition at room temperature. Weinvestigate the dimerisation and the magnetic structure of TiPO4 at high pressure.As pressure is increased further, TiPO4 goes through a metal to insulatortransition before an eventual crystallographic phase transition. Remarkably, thenew high pressure phases are found to be insulators; the Mott insulating stateis restored. MAX phases are layered materials that combinemetallic and ceramic properties and feature layers of M-metal and X-C or N atomsinterconnected by A-group atoms. Magnetic MAX-phases with their low dimensionalmagnetism are promising candidates for applications in e.g., spintronics.The validity of various theoretical approaches are discussed in connection tothe magnetic MAX-phase Mn2GaC. Using DFT and DFT + DMFT we consider the hightemperature paramagnetic state, and whether the magnetic moments are formed bylocalized or itinerant electrons. Ett materials makroskopiska egenskaper, såsom ledningsförmåga, magnetiska egenskaper, kristallstrukturparametrar, etc. är relaterade till, eller till och med bestämda av elektronernas konfiguration, vilken karakteriseras av elektronstrukturen. Genom att ändra förhållandena, till exempel via tryck, temperatur, magnetiska och/eller elektriska fält, dopning, etc. är det möjligt att modifiera elektronstrukturen hos ett material, och därigenom inducera fasövergångar mellan olika magnetiska och elektron-tillstånd. Mott metall-till-isolator övergången är ett berömt exempel på en fasövergång, då ett material genomgår en omfattande, ofta flera tiopotenser, förändring i ledningsförmåga, orsakad av samspelet mellan ambulerande och lokaliserade laddningsbärare. Vid en elektronisk-topologisk övergång (eng. electronic topological transition, ETT) sker förändringar i elektronernas energifördelning vilket modifierar materialets Fermi-yta. I den här avhandlingen undersöks dylika övergångar i olika material, från rena grundämnen till komplicerade föreningar. Flera olika toppmoderna beräkningsmetoder används för att redogöra för samspelet mellan elektroniska fasövergångar och egenskaper hos riktiga material. Täthetsfunktionalterori (eng. density functional theory, DFT), samt DFT + U, har används för att beräkna strukturella egenskaper. Lämplighetsgraden i att använda nyligen publicerade exchangecorrelation- funktionaler, såsom SCAN (eng. strongly constrained and appropriately normed), för att beskriva magnetiska grundämnen undersöks även. För att inkludera dynamiska elektronkorrelationer använder vi metoden DFT + dynamisk medelfältteori (eng. dynamical mean field theory, DMFT). Experiment utförda på hcp-Os vid högt tryck visar underliga hopp i kvoten mellan gitterparametrar. Tidigare beräkningar har indikerat att dessa övergångar kan vara relaterade till elektronisk-topologiska övergångar och korsande av kärntillstånd. I den här avhandlingen visas också att korsning av kärntillstånden är en generell egenskap hos tunga övergångsmetaller. Därför utförs röntgenabsorptionsexperiment på Ir för att leta efter tecken på denna typ av övergång. Övergångsmetalloxiden NiO har sedan länge förutspåtts genomgå en isolator till metall Mott-övergång. Det har föreslagits att denna övergång sker vid höga tryck i samband med att materialets magnetiska ordning försvinner och en strukturell övergång sker. I samarbete med experimentalister letar vi efter denna övergång genom att studera röntgenabsorptionsspektra och det magnetiska hyperfina fältet. Vi ser inga indikationer på en Mott-övegång, upp till ett tryck på 280 GPa. Det har föreslagits att Mott-isolatorn TiPO4 genomgår en så kallad spin-Peierls-övergång, vid rumstemperatur, när tryck appliceras. Vi undersöker dimeriseringen och den magnetiska strukturen i TiPO4 som funktion av tryck. Vid höga tryck genomgår TiPO4 ytterligare övergångar, från en isolerande till en metallisk fas för att slutligen genomgå en strukturell övergång. De nya högtrycksfaserna visar sig anmärkningsvärt vara Mott-isolatorer. MAX-faser är en grupp material med specifik kristallstruktur, som kombinerar egenskaper från keramiska material och metaller. En MAX-fas består av lager av M –metall-atomer – och X – kol- eller kväveatomer – vilka sammanbinds av atomer från grupp A. Magnetiska MAX-faser som visar magnetiska egenskaper, liknande de för lågdimensionella material, är lovande kandidater för applikation inom exempelvis spinntronik. Den här avhandlingen undersöker lämplighetsgraden i att använda diverse teoretiska metoder för att beskriva magnetiska MAX-faser. Med hjälp av DFT och DFT + DMFT undersöker vi den paramagnetiska högtemperaturfasen och huruvida de magnetiska momenten bildas av lokaliserade eller ambulerande elektroner.