Developments in the density functional theory and the methods of electronic structure calculations have made it possible to carry out ab-initio studies of a variety of materials efficiently and at a predictable level. This book covers many of those state-of-the-art developments and their applications to ordered and disordered materials, surfaces and interfaces and clusters, etc.

In the slightly more than thirty years since its formulation, the Hubbard model has become a central component of modern many-body physics. It provides a paradigm for strongly correlated, interacting electronic systems and offers insights not only into the general underlying mathematical structure of many-body systems but also into the experimental behavior of many novel electronic materials. In condensed matter physics, the Hubbard model represents the simplest theoret ical framework for describing interacting electrons in a crystal lattice. Containing only two explicit parameters - the ratio ("Ujt") between the Coulomb repulsion and the kinetic energy of the electrons, and the filling (p) of the available electronic band - and one implicit parameter - the structure of the underlying lattice - it appears nonetheless capable of capturing behavior ranging from metallic to insulating and from magnetism to superconductivity. Introduced originally as a model of magnetism of transition met als, the Hubbard model has seen a spectacular recent renaissance in connection with possible applications to high-Tc superconductivity, for which particular emphasis has been placed on the phase diagram of the two-dimensional variant of the model. In mathematical physics, the Hubbard model has also had an essential role. The solution by Lieb and Wu of the one-dimensional Hubbard model by Bethe Ansatz provided the stimulus for a broad and continuing effort to study "solvable" many-body models. In higher dimensions, there have been important but isolated exact results (e. g. , N agoaka's Theorem).

Timely information on scientific and engineering developments occurring in laboratories around the world provides critical input to maintaining the economic and technological strength of the United States. Moreover, sharing this information quickly with other countries can greatly enhance the productivity of scientists and engineers. These are some of the reasons why the National Science Foundation (NSF) has been involved in funding science and technology assessments comparing the United States and foreign countries since the early 1980s. A substantial number of these studies have been conducted by the World Technology Evaluation Center (WTEC) managed by Loyola College through a cooperative agreement with NSF. The National Science and Technology Council (NSTC), Committee on Technology's Interagency Working Group on NanoScience, Engineering and Technology (CT/IWGN) worked with WTEC to develop the scope of this Nanostucture Science and Technology report in an effort to develop a baseline of understanding for how to strategically make Federal nanoscale R&D investments in the coming years. The purpose of the NSTC/WTEC activity is to assess R&D efforts in other countries in specific areas of technology, to compare these efforts and their results to U. S. research in the same areas, and to identify opportunities for international collaboration in precompetitive research. Many U. S. organizations support substantial data gathering and analysis efforts focusing on nations such as Japan. But often the results of these studies are not widely available. At the same time, government and privately sponsored studies that are in the public domain tend to be "input" studies.

This book has grown out of our shared experience in the development of the Stanford Synchrotron Radiation Laboratory (SSRL), based on the electron-positron storage ring SPEAR at the Stanford Linear Accelerator Center (SLAC) starting in Summer, 1973. The immense potential of the photon beam from SPEAR became obvious as soon as experiments using the beam started to run in May, 1974. The rapid growth of interest in using the beam since that time and the growth of other facilities using high-energy storage rings (see Chapters 1 and 3) demonstrates how the users of this source of radiation are finding applications in an increasingly wide variety of fields of science and technology. In assembling the list of authors for this book, we have tried to cover as many of the applications of synchrotron radiation, both realized already or in the process of realization, as we can. Inevitably, there are omissions both through lack of space and because many projects are at an early stage. We thank the authors for their efforts and cooperation in producing what we believe is the most comprehensive treatment of synchrotron radiation research to date.