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Concepts in Electron Correlation

Author: Alex C. Hewson

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 364

ISBN-13: 9401002134

The NATO sponsored Advanced Research Workshop on "Concepts in Electron Correlation" took place on the Croatian island of Hvar during the period from the 29th of September to the 3rd of October, 2002. The topic of electron correlation is a fundamental one in the field of condensed matter, and one that is being very actively studied both experimentally and theoretically at the present time. The manifestations of electron cor relation are diverse, and play an important role in systems ranging from high temperature superconductors, heavy fermions, manganite compounds with colossal magnetoresistance, transition metal compounds with metal insulator transitions, to mesoscopic systems and quantum dots. The aim of the workshop was to provide an opportunity for a dialogue between exper imentalists and theoreticians to assess the current state of understanding, and to set an agenda for future work. There was also a follow-up workshop on the same topic where the presentations included more background and introductory material for younger researchers in the field. The papers presented in these proceedings clearly demonstrate the di versity of current research on electron correlation. They show that real progress is being made in characterising systems experimentally and in developing theoretical approaches for a quantitative comparison with ex periment. The more one learns, however, the more there is to understand, and many of the contributions help to map out the territory which has yet to be explored. We hope that the articles in this volume will be a stimulus for such future work.

Electron Correlation in Molecules

Author: S. Wilson

Publisher: Courier Corporation

Published: 2014-07-01

Total Pages: 305

ISBN-13: 0486150224

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Electron correlation effects are of vital significance to the calculation of potential energy curves and surfaces, the study of molecular excitation processes, and in the theory of electron-molecule scattering. This text describes methods for addressing one of theoretical chemistry's central problems, the study of electron correlation effects in molecules. Although the energy associated with electron correlation is a small fraction of the total energy of an atom or molecule, it is of the same order of magnitude as most energies of chemical interest. If the solution of quantum mechanical equations from first principles is to provide an accurate quantitative prediction, reliable techniques for the theoretical determination of the effect of electron correlation on molecular properties are therefore important. To that end, this text explores molecular electronic structure, independent electron models, electron correlation, the linked diagram theorem, group theoretical aspects, the algebraic approximation, and truncation of expansions for expectation values.

New Concepts in Electron Correlation with Application to Extended Systems

Author:

Publisher:

Published: 1998

Total Pages: 10

ISBN-13:

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The objective of our work for ONR has been to develop and apply new, correlated electronic structure methods for infinite periodic systems. The methods of interest include many body perturbation theory (MBPT) and its infinite order coupled cluster generalizations and complementary density functional methods. Today we routinely do highly correlated studies of molecules (including making reliable predictions of structure, photoelectron, vibrational, and electronic spectra). The next frontier in electronic structure theory is the treatment (with the same level of confidence) of polymers, surfaces, and crystals, which are semiconductors or insulators and are collectively termed "extended systems." The current paradigm for molecules is SCF, MBPT(2), CCSD, CCSD(T), CCSDT, and full CI. Though convergence is not monotonic, such a sequence, augmented by experience and approximate error bars, typically offers purely ab inito, extrapolated solutions that are predictive. In contrast, no such paradigm exists for extended systems. Furthermore, there is no full CI so only high-level CC methods can offer reference results. The only methods currently available for extended systems are periodic Hartree Fock (i.e., SCF) and density functional theory (DFT), usually in the local density approximation (LDA). The former lacks the critical electron correlation effects responsible for so many of the interesting phenomena in solids, from band gaps to high Tc superconductivity, while the latter might introduce some correlation effects, but an unclear amount. In fact, the greatest weakness of DFT is that, unlike the above CC/MBPT paradigm, there is no way to systematically converge to the correct result.

Electron Correlation in Molecules and Condensed Phases

Author: Norman H. March

Publisher: Springer Science & Business Media

Published: 1996-10-31

Total Pages: 416

ISBN-13: 9780306448447

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This reference describes the latest research on correlation effects in the multicenter problems of atoms, molecules, and solids. The author utilizes first- and second-order matrices, including the important observable electron density rho(r), and the Green function for discussing quantum computer simulations. With its focus on concepts and theories, this volume will benefit experimental physicists, materials scientists, and physical and inorganic chemists as well as graduate students.

Electron Correlations in Molecules and Solids

Author: Peter Fulde

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 492

ISBN-13: 3642578098

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Dieser Titel verbindet die Festkörpertheorie mit der Quantenchemie. Neue Konzepte der Vielteilchen-Verarbeitung und Korrelations-Effekte, normale quantenchemische Verfahren mit Projektionstechniken, Greensche Funktionen und Monte-Carlo-Methoden werden erarbeitet. Anwendungsbereiche der Molekültheorie, von Halbleitern, supraleitender high-Tc-Materialien, etc., werden vorgestellt.

Electron Correlations In The Solid State

Author: Norman H March

Publisher: World Scientific Publishing Company

Published: 1999-12-13

Total Pages: 452

ISBN-13: 1911298941

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This invaluable book deals with the many-electron theory of the solid state. Mastery of the material in it will equip the reader for research in areas such as high-temperature superconductors and the fractional quantum Hall effect. The whole book has been designed to provide the diligent reader with a wide variety of approaches to many-electron theory.The level of the book is suitable for research workers and higher-degree students in a number of disciplines, embracing theoretical physics, materials science and solid-state chemistry. It should be useful not only to theorists in these areas but also to experimental scientists who desire to orient their programmes to address outstanding questions raised by many-body theory.

Electron Correlations in Solids, Molecules, and Atoms

Author: Jozef T. Devreese

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 440

ISBN-13: 1461334977

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From July 20 till 31, 1981, the Advanced Study Institute on "Electron Correlations in Solids, Molecules and Atoms", sponsored by NATO, was held at the University of Antwerpen (U.I.A.), in the Conference Center Corsendonk. In the last few years, the problem of many-electron correlations has gained renewed attention, due to recent experimental and theoretic al developments. From the theoretical point of view, more sophisticated treatments of the homogeneous electron gas model evolved, including dynamical aspects of the electron correlation in the dielectric response. Furthermore, the homogeneous electron gas, which served as a model for simple metals, was extended to include spin- and charge-density waves and phasons. The concept of elementary excitations too was introduced not only in perfectly ordered metallic crystals, but also in magnetic alloys, in liquid metals and alloys, in semiconductors, and even in molecules and atoms. Fairly accurate quantitative calculations of these effects recently became possible, ranging from plasmon frequencies in atoms, over dielectric response of semiconduc tors and resistivity in magnetic alloys to electron-hole liquids and their phase separation. The recent technological evolution allowed for more accurate measurements in previously unaccessible domains, e.g. X-ray scatter ing and fast electron energy loss at large wavevector. Moreover, these new developments opened new perspectives in physics, accompany ing or even introducing the new concepts which also evolved in the theory.

Structure and Dynamics of Atoms and Molecules: Conceptual Trends

Author: Jean-Louis Calais

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 269

ISBN-13: 9401102635

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The rivers run into the sea, yet the sea is not full Ecclesiastes What is quantum chemistry? The straightforward answer is that it is what quan tum chemists do. But it must be admitted, that in contrast to physicists and chemists, "quantum chemists" seem to be a rather ill-defined category of scientists. Quantum chemists are more or less physicists (basically theoreticians), more or less chemists, and by and large, computationists. But first and foremost, we, quantum chemists, are conscious beings. We may safely guess that quantum chemistry was one of the first areas in the natural sciences to lie on the boundaries of many disciplines. We may certainly claim that quantum chemists were the first to use computers for really large scale calculations. The scope of the problems which quantum chemistry wishes to answer and which, by its unique nature, only quantum chemistry can answer is growing daily. Retrospectively we may guess that many of those problems meet a daily need, or are say, technical in some sense. The rest are fundamental or conceptual. The daily life of most quantum chemists is usually filled with grasping the more or less technical problems. But it is at least as important to devote some time to the other kind of problems whose solution will open up new perspectives for both quantum chemistry itself and for the natural sciences in general.

Electron Correlation in Molecules

Author: Stephen Wilson

Publisher:

Published: 2014-01-01

Total Pages: 281

ISBN-13: 9781306937856

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Electron Correlations and Materials Properties 2

Author: A. Gonis

Publisher: Springer Science & Business Media

Published: 2013-03-09

Total Pages: 413

ISBN-13: 1475737602

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This is the second in a series of "International Workshops on Electron Correlations and Materials Properties. " The aim of this series of workshops is to provide a periodic (triennial) and in-depth assessment of advances in the study and understanding of the effects that electron-electron interactions in solids have on the determination of measurable properties of materials. The workshop is structured to include exposure to experimental work, to phenomenology, and to ab initio theory. Since correlation effects are pervasive the workshop aims to concentrate on the identification of promising developing methodology, experimental and theoretical, addressing the most critical frontier issues of electron correlations on the properties of materials. This series of workshops is distinguished from other topical meetings and conferences in that it strongly promotes an interdisciplinary approach to the study of correlations, involving the fields of quantum chemistry, physics, and materials science. The First Workshop was held June 28-July 3, 1998, and a proceedings of the workshop was published by KluwerlPlenum. The Second Workshop was held June 24- 29,2001, and this volume contains the proceedings of that scientific meeting. Through the publications of proceedings, the workshop attempts to disseminate the information gathered during the discussions held at the Workshop to the wider scientific community, and to establish a record of advances in the field.