Mikael Ciftan – författare

This volume, the proceedings of the First International Workshop on Electron Correlations and Materials Properties, held in June 28-July 3, 1998, provides experimental evidence of the effects of correlation on the physical, chemical, and mechanical properties of materials, as well as the theoretical/computational methodology that has been developed for their study. The volume focuses in particular on understanding in detail the quantum nature of the electronic states in solids pertaining to correlation effects and their impact on observable behaviour as provided by both band-theoretical and many-body approaches.

This volume contains the proceedings of the Second International Workshop on Electron Correlations and Materials Properties, held in Rhodes, Greece during June, 2001. 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.

This volume contains the proceedings of the Second International Workshop 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.

Over the last thirty years or so, the attempts to identify the electronic origins of materials properties have proceeded along two distinct and apparently divergent methodologies. On the one-hand, so-called single-particle methods are based on the study of a single electron moving in an effective field formed by the other electrons and the nuclei in the system. Band theory, as this approach is referred to, has had impressive successes in determining the equilibrium properties, such as structural stability, volume, and charge densities, of specific materials, notably metals. Today, even coherent phase diagrams (based on a single underlying lattice) for binary metallic alloys can be studied with considerable accuracy. In spite of its serious and well-understood limitations regarding the handling of correlations, band theory has been embraced by the materials scientist. Its single-particle nature endows the method with an economy of concepts which leads to a clear identification of mechanisms driving physical behavior at the electronic level. This perceived clarity often tends to override legitimate concerns regarding the validity of the method or its ability to correctly identify the mechanisms in the first place. The alternative methodology pursued in the study of quantum systems consists of what can be referred to as conventional many-body theory. This methodology is based on attempts to study explicitly the effects of interparticle correlations using a number of different formal approaches, including but not limited to, perturbation methods, Green-function equation of motion methods, configuration interactions, quantum Monte Carlo, and others.