Mikael Ciftan – författare

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.

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.

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.

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.

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.

During the past few decades we have witnessed at least two major innovations in science which have had substantial impact on technology as well as science itself, pervasive enough to modify many facets of our daily lives. We refer, of course, to the tran­ sistor and the laser. It is striking that now with the advent of optical bistability we may have opened the door to another such field, which combines these two aspects (transistor and laser) and has the possibility for important device applications as well as providing a unique window into the as yet not thoroughly explored frontiers of nonequilibrium statistical physics. This has prompted us to organize an international conference on the subject of optical bistability to provide an adequate means for assessing the current state of the art of this important field and to stimulate further significant developments by means of in­ tense technical exchange and interaction among the leading scien­ tists in this subject area.

During the past few decades we have witnessed at least two major innovations in science which have had substantial impact on technology as well as science itself, pervasive enough to modify many facets of our daily lives. We refer, of course, to the tran­ sistor and the laser. It is striking that now with the advent of optical bistability we may have opened the door to another such field, which combines these two aspects (transistor and laser) and has the possibility for important device applications as well as providing a unique window into the as yet not thoroughly explored frontiers of nonequilibrium statistical physics. This has prompted us to organize an international conference on the subject of optical bistability to provide an adequate means for assessing the current state of the art of this important field and to stimulate further significant developments by means of in­ tense technical exchange and interaction among the leading scien­ tists in this subject area.