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.

Inhalt

Preface. Superconductivity by kinetic energy saving? D. van der Marel, et al. Josephson effect in the cuprates: microscopic implications; R. Hlubina. Ruthenates: Unconventional superconductivity and magnetic properties; M. Sigrist. Real structure of perovskites looked at from the band structure point of view; K.-D. Schotte, C.T. Liang. Towards models of magnetic interactions in the cuprates; H. Eschrig, et al. c-axis intra-layer couplings in the CuO2 planes of high-Tc cuprates; J. Röhler. Spectral functions and pseudogap in a model of strongly correlated electrons; P. Prelovsek, A. Ramsak. Mott insulator to superconductor via pressure RVB theory and prediction of new systems; G. Baskaran. Exploring the phase diagram of the quasi-2D organic superconductors kappa-(BEDT-TTF)2X; M. Lang, et al. Enhancement of superconductivity by strong correlations: a model study; M. Fabrizio, et al. Inelastic light scattering and the correlated metal-insulator transition; J.K. Freericks, et al. Orbital physics versus spin physics: the orbital-Hubbard model; L.F. Feiner, A.M. Olés. Quasiparticles in photemission spectra of manganites; J. Bala, A.M. Olés. Metals near a zero-temperature magnetic instability; H. van Löneysen. Heavily doped semiconductors: magnetic moments, electron-electron interactions and the metal-insulator trnsition; H. van Löneysen. Competition and coexistence of magnetic and quadrupolar ordering; P. Fazekas, A Kiss. Low dimensional spin systems in high magnetic fields: spin-phonon interaction; B. Lüthi, et al. Taxonomy of electron glasses; N.P. Armitage, et al. Renormalization group approaches for systems with electron-electron andelectron-phonon interactions; A.C. Hewson, D. Meyer. Quantum phase transitions in models of magnetic impurities; R. Bulla, M. Vojta. Instability of the Fermi-liquid fixed point in an extended Kondo model; M. Lavagna, et al. Projection of the Kondo effect by resonant eigenstates inside a circular quantum corral; A. Lobos, A.A. Aligia. Nonequilibrium electron transport through nanostructures: correlation effects; P. Wölfle, et al. Quantum fluctuations and electronic transport through strongly interacting quantum dots; T.A. Costi. Properties of correlated nanoscopic systems from the combined exact diagonalization ab initio method; J. Spalek, et al. On the multichannel-channel Anderson impurity model of uranium compounds; N. Andrei, C.J. Bolech. Anomalous behavior in rare-earth and actinide systems; B. Coqblin. Describing the valence-change transition by the DMFT solution of the Falicov-Kimball model; V. Zlatic, J.K. Freericks. Neutron spectroscopy of valence fluctuation compounds of Cerium and Ytterbium; A.P. Murani. Generalizations of DFMT, CPA and NCA; H. Keiter, et al. Itinerant ferromagnetism for mixed valence systems; J. Bonca, et al. Transport properties of heavy fermion systems; C. Grenzebach, G. Czycholl. Transport properties of correlated electrons in high dimensions; N. Blümer, P.G.J.van Dongen. From CeIn3 to PuCoGa5: trends in heavy fermion superconductivity; J.L. Sarrao, J.D. Thompson. Do we understand electron correlation effects in Gadolinium based intermetallic compounds? E.V. Sampathkumaran, R. Mallik. Optical properties of correlated systems; L. Degeorgi. Quasiparticle undressing: a new route to collective effects in solids; J.E. Hirsch. List of Contributors.