Physics of Solids and Liquids – serie

The theory of the inhomogeneous electron gas had its origin in the Thomas­ Fermi statistical theory, which is discussed in the first chapter of this book. This already leads to significant physical results for the binding energies of atomic ions, though because it leaves out shell structure the results of such a theory cannot reflect the richness of the Periodic Table. Therefore, for a long time, the earlier method proposed by Hartree, in which each electron is assigned its own personal wave function and energy, dominated atomic theory. The extension of the Hartree theory by Fock, to include exchange, had its parallel in the density description when Dirac showed how to incorporate exchange in the Thomas-Fermi theory. Considerably later, in 1951, Slater, in an important paper, showed how a result similar to but not identical with that of Dirac followed as a simplification of the Hartree-Fock method. It was Gombas and other workers who recognized that one could also incorporate electron correlation consistently into the Thomas-Fermi-Dirac theory by using uniform electron gas relations locally, and progress had been made along all these avenues by the 1950s.

This book has its origins in the 1982 Spring College held at the Interna­ tional Centre for Theoretical Physics, Miramare, Trieste. The primary aim is to give a broad coverage of liquids and amorphous solids, at a level suitable for graduate students and research workers in condensed-matter physics, physical chemistry, and materials science. The book is intended for experimental workers with interests in the basic theory. While the topics covered are many, it was planned to place special emphasis on both static structure and dynamics, including electronic transport. This emphasis is evident from the rather complete coverage of the determination of static structure from both diffraction experiments and, for amorphous solids especially, from model building. The theory of the structure of liquids and liquid mixtures is then dealt with from the standpoint of, first, basic statistical mechanics and, subsequently, pair potentials constructed from the electron theory of simple metals and their alloys. The discussion of static structure is completed in two chapters with rather different emphases on liquid surfaces and interfaces. The first deals with the basic statistical mechanics of neutral and charged interfaces, while the second is concerned with solvation and double-layer effects. Dynamic structure is introduced by a comprehensive discussion of single-particle motion in liquids. This is followed by the structure and dynamics of charged fluids, where again much basic statistical mechanics is developed.

This book is concerned primarily with the fundamental theory underlying the physical and chemical properties of crystalIine semiconductors. After basic introductory material on chemical bonding, electronic band structure, phonons, and electronic transport, some emphasis is placed on surface and interfacial properties, as weil as effects of doping with a variety of impurities. Against this background, the use of such materials in device physics is examined and aspects of materials preparation are discussed briefty. The level of presentation is suitable for postgraduate students and research workers in solid-state physics and chemistry, materials science, and electrical and electronic engineering. Finally, it may be of interest to note that this book originated in a College organized at the International Centre for Theoretical Physics, Trieste, in Spring 1984. P. N. Butcher N. H. March M. P. Tosi vii Contents 1. Bonds and Bands in Semiconductors 1 E. Mooser 1. 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. 2. The Semiconducting Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. 3. Bond Approach Versus Band Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1. 4. Construction of the Localized X by Linear Combination of n Atomic Orbitals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 1. 5. The General Octet Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 1. 6. The Aufbau-Principle of the Crystal Structure of Semiconductors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 1. 7. A Building Principle for Polyanionic Structures . . . . . . . . . . . . . . . . . . . . . . 29 I. H. Structural Sorting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 1. 9. Chemical Bonds and Semiconductivity in Transition-Element Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 1. 10. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 2. Electronic Band Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 G. Grosso 2. 1. Two Different Strategies for Band-Structure Calculations . . . . . . . 55 2. 2. The Tight-Binding Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

This volume is concerned with the theoretical description of patterns and instabilities and their relevance to physics, chemistry, and biology. More specifically, the theme of the work is the theory of nonlinear physical systems with emphasis on the mechanisms leading to the appearance of regular patterns of ordered behavior and chaotic patterns of stochastic behavior. The aim is to present basic concepts and current problems from a variety of points of view. In spite of the emphasis on concepts, some effort has been made to bring together experimental observations and theoretical mechanisms to provide a basic understanding of the aspects of the behavior of nonlinear systems which have a measure of generality. Chaos theory has become a real challenge to physicists with very different interests and also in many other disciplines, of which astronomy, chemistry, medicine, meteorology, economics, and social theory are already embraced at the time of writing. The study of chaos-related phenomena has a truly interdisciplinary charac­ ter and makes use of important concepts and methods from other disciplines. As one important example, for the description of chaotic structures the branch of mathematics called fractal geometry (associated particularly with the name of Mandelbrot) has proved invaluable. For the discussion of the richness of ordered structures which appear, one relies on the theory of pattern recognition. It is relevant to mention that, to date, computer studies have greatly aided the analysis of theoretical models describing chaos.

This lovely little book will take off and fly on its own power, but the author has asked me to write a few words, and one should not say no to a friend. Specific topics in fractal geometry and its applications have already benefited from several excellent surveys of moderate length, and gossip and preliminary drafts tell us that we shall soon see several monographic treatments of broader topics. For the teacher, however, these surveys and monographs are not enough, and an urgent need for more helpful books has been widely recognized. To write such a book is no easy task, but Jens Feder meets the challenge head on. His approach combines the old Viking's willingness to attack many difficulties at the same time, and the modern Norwegian's ability to achieve fine balance between diverging needs. lowe him special gratitude for presenting the main facts about R/ S analysis of long-run dependence; now a wide scientific public will have access to a large group of papers of mine that had until this day remained fairly confidential. Last but not least, we are all grateful to Jens for not having allowed undue personal modesty to deprive us of accounts of his own group's varied and excellent work. He did not attempt to say everything, but what he said is just fine. Benoit B. Mandelbrot Physics Department, IBM Thomas J.

This textbook is for a course in advanced solid-state theory. It is aimed at graduate students in their third or fourth year of study who wish to learn the advanced techniques of solid-state theoretical physics. The method of Green's functions is introduced at the beginning and used throughout. Indeed, it could be considered a book on practical applications of Green's functions, although I prefer to call it a book on physics. The method of Green's functions has been used by many theorists to derive equations which, when solved, provide an accurate numerical description of many processes in solids and quantum fluids. In this book I attempt to summarize many of these theories in order to show how Green's functions are used to solve real problems. My goal, in writing each section, is to describe calculations which can be compared with experiments and to provide these comparisons whenever available. The student is expected to have a background in quantum mechanics at the level acquired from a graduate course using the textbook by either L. I. Schiff, A. S. Davydov, or I. Landau and E. M. Lifshiftz. Similarly, a prior course in solid-state physics is expected, since the reader is assumed to know concepts such as Brillouin zones and energy band theory. Each chapter has problems which are an important part of the lesson; the problems often provide physical insights which are not in the text. Sometimes the answers to the problems are provided, but usually not.

During the past decade the theoretical physics community has learned how to evaluate accurately polarizabilities and susceptibilities for many-electron systems such as atoms, solids, and liquids. The most accurate numerical technique employs a method often called the Time-Dependent Local Density Approximation, which is abbreviated TDLDA. The present volume is a review of recent research on the theory of po­ larizabilities and susceptibilities. Both authors have been doing these cal­ culations. However, this review surveys the entire field, summarizing the research of many contributors. The application of an external field, either ac or de, will induce a dipole moment which can be calculated and compared with experiment. For mod­ erately strong fields, both linear and nonlinear processes contribute to the moment. We cover topics such as polarizability, hyperpolarizability, pho­ toionization, phonons, and piezoelectricity. Density functional theory in the Local Density Approximation (LDA) has been shown to be a very accurate method for calculating ground state prop­ erties of electronic system. For static external fields, the induced moments are properties of the ground state. Then the calculation of the polarizability · is very accurate. For ac fields, the moment is not part of the ground state. However, the TDLDA methods are still very accurate.

The majority of the chapters in this volume represent a series of lectures. that were given at a workshop on quantum transport in ultrasmall electron devices, held at San Miniato, Italy, in March 1987. These have, of course, been extended and updated during the period that has elapsed since the workshop was held, and have been supplemented with additional chapters devoted to the tunneling process in semiconductor quantum-well structures. The aim of this work is to review and present the current understanding in nonequilibrium quantum transport appropriate to semiconductors. Gen­ erally, the field of interest can be categorized as that appropriate to inhomogeneous transport in strong applied fields. These fields are most likely to be strongly varying in both space and time. Most of the literature on quantum transport in semiconductors (or in metallic systems, for that matter) is restricted to the equilibrium approach, in which spectral densities are maintained as semiclassical energy­ conserving delta functions, or perhaps incorporating some form of collision broadening through a Lorentzian shape, and the distribution functions are kept in the equilibrium Fermi-Dirac form. The most familiar field of nonequilibrium transport, at least for the semiconductor world, is that of hot carriers in semiconductors.

Presenting the latest advances in artificial structures, this volume discusses in-depth the structure and electron transport mechanisms of quantum wells, superlattices, quantum wires, and quantum dots. It will serve as an invaluable reference and review for researchers and graduate students in solid-state physics, materials science, and electrical and electronic engineering.

Applying a unified quantum approach, contributors offer fresh insights into the theoretical developments in the excitation energy transfer processes in condensed matter. This comprehensive volume examines Frenkel and Wannier excitonic processes; rates of excitonic processes; theory of laser sputter and polymer ablation; and polarons, excitonic polarons and self-trapping.

This book had its origins in lectures presented at EPFL, Lausanne, during two separate visits (the most recent being to IRRMA). The author is most grateful to Professors A. Baldereschi, R. Car, and A. Quattropani for making these visits possible, and for the splendidly stimulating environment provided. Professors S. Baroni and R. Resta also influenced considerably the presentation of material by constructive help and comments. Most importantly, Chapters 4 and 5 were originally prepared for a review article by Professor G. Senatore, then at Pavia and now in Trieste, and myself for Reviews of Modem Physics (1994). In the 'course of this collaboration, he has taught me a great deal, especially about quantum Monte Carlo procedures, and Chapter 5 is based directly on this review article. Also in Chapter 4, my original draft on Gutzwiller's method has been transformed by his deeper understanding; again this is reflected directly in Chapter 4; especially in the earlier sections. In addition to the above background, it is relevant here to point out that, as a backcloth for the present, largely "state of the art," account, there are two highly relevant earlier books: The Many-body Problem in Quantum Mechanics with W.

In this new work, the focus is on the dynamical response of metal electrons to several types of incident electromagnetic fields. The author, an eminent theorist, discusses Time-Dependent Local Density Approximation's importance in both elucidating electronic surface excitations and describing the ground state properties of electronic systems. Chapters detail theoretical formulations and computational procedures, covering such areas as single-particle and collective modes, spatial distribution of the induced surface charges, and local electric fields. Excitation spectra are shown for a variety of clean simple metals, noble metals, chemisorbed overlayers, charged surfaces, and small metal particles.

The first, second, and third editions of this book seem to occur at ten year intervals. The intent is to keep the book up-to-date. Many-body theory is a field which continually evolves in time. Journals only publish new results, conferences only invite speakers to report new phenomena, and agencies only fund scientists to do new physics. Today's physics is old hat by tomorrow. Students want to learn new material, and textbooks must be modified to keep up with the times. The early chapters in this book teach the techniques of many-body theory. They are largely unchanged in format. The later chapters apply the techniques to specific problems. The third edition increases the number of applications. New sections have been added, while old sections have been modified to include recent applications. The previous editions were set in type using pre-computer technology. No computer file existed of the prior editions. The publisher scanned the second edition and gave me a disk with the contents. This scan recorded the words accurately and scrambled the equations into unintelligible form. So I retyped the equations using LaTeX. Although tedious, it allowed me to correct the infinite numbers of typographical errors in the previous edition. The earlier typesetting methods did not permit such corrections. The entire book was edited sentence-by­ sentence. Most old sections of the book were shortened by editing sentences and paragraphs.

Theoretical understanding of electronic properties of metallic alloys is of great importance from both fundamental and technological points of view. This text gives a brief account of the crystal structure of both the pure metals and metals with impurities. Physical effects produced by impurities in metals are described, as is the electronic structure of pure simple and transition metals with special reference to rare-earth metals.

It has been almost thirty years since the publication of a book that is entirely dedicated to the theory, description, characterization and measurement of the thermal conductivity of solids. The recent discovery of new materials which possess more complex crystal structures and thus more complicated phonon scattering mechanisms have brought innovative challenges to the theory and experimental understanding of these new materials. With the development of new and novel solid materials and new measurement techniques, this book will serve as a current and extensive resource to the next generation researchers in the field of thermal conductivity. This book is a valuable resource for research groups and special topics courses (8-10 students), for 1st or 2nd year graduate level courses in Thermal Properties of Solids, special topics courses in Thermal Conductivity, Superconductors and Magnetic Materials, and to researchers in Thermoelectrics, Thermal Barrier Materials and Solid State Physics.

In this new work, the focus is on the dynamical response of metal electrons to several types of incident electromagnetic fields. The author, an eminent theorist, discusses Time-Dependent Local Density Approximation's importance in both elucidating electronic surface excitations and describing the ground state properties of electronic systems. Chapters detail theoretical formulations and computational procedures, covering such areas as single-particle and collective modes, spatial distribution of the induced surface charges, and local electric fields. Excitation spectra are shown for a variety of clean simple metals, noble metals, chemisorbed overlayers, charged surfaces, and small metal particles.

The first, second, and third editions of this book seem to occur at ten year intervals. The intent is to keep the book up-to-date. Many-body theory is a field which continually evolves in time. Journals only publish new results, conferences only invite speakers to report new phenomena, and agencies only fund scientists to do new physics. Today's physics is old hat by tomorrow. Students want to learn new material, and textbooks must be modified to keep up with the times. The early chapters in this book teach the techniques of many-body theory. They are largely unchanged in format. The later chapters apply the techniques to specific problems. The third edition increases the number of applications. New sections have been added, while old sections have been modified to include recent applications. The previous editions were set in type using pre-computer technology. No computer file existed of the prior editions. The publisher scanned the second edition and gave me a disk with the contents. This scan recorded the words accurately and scrambled the equations into unintelligible form. So I retyped the equations using LaTeX. Although tedious, it allowed me to correct the infinite numbers of typographical errors in the previous edition. The earlier typesetting methods did not permit such corrections. The entire book was edited sentence-by­ sentence. Most old sections of the book were shortened by editing sentences and paragraphs.

It has been almost thirty years since the publication of a book that is entirely dedicated to the theory, description, characterization and measurement of the thermal conductivity of solids. The recent discovery of new materials which possess more complex crystal structures and thus more complicated phonon scattering mechanisms have brought innovative challenges to the theory and experimental understanding of these new materials. With the development of new and novel solid materials and new measurement techniques, this book will serve as a current and extensive resource to the next generation researchers in the field of thermal conductivity. This book is a valuable resource for research groups and special topics courses (8-10 students), for 1st or 2nd year graduate level courses in Thermal Properties of Solids, special topics courses in Thermal Conductivity, Superconductors and Magnetic Materials, and to researchers in Thermoelectrics, Thermal Barrier Materials and Solid State Physics.

This textbook is for a course in advanced solid-state theory. It is aimed at graduate students in their third or fourth year of study who wish to learn the advanced techniques of solid-state theoretical physics. The method of Green's functions is introduced at the beginning and used throughout. Indeed, it could be considered a book on practical applications of Green's functions, although I prefer to call it a book on physics. The method of Green's functions has been used by many theorists to derive equations which, when solved, provide an accurate numerical description of many processes in solids and quantum fluids. In this book I attempt to summarize many of these theories in order to show how Green's functions are used to solve real problems. My goal, in writing each section, is to describe calculations which can be compared with experiments and to provide these comparisons whenever available. The student is expected to have a background in quantum mechanics at the level acquired from a graduate course using the textbook by either L. I. Schiff, A. S. Davydov, or I. Landau and E. M. Lifshiftz. Similarly, a prior course in solid-state physics is expected, since the reader is assumed to know concepts such as Brillouin zones and energy band theory. Each chapter has problems which are an important part of the lesson; the problems often provide physical insights which are not in the text. Sometimes the answers to the problems are provided, but usually not.

The problem of molecules interacting with metal surfaces has for a very long time been recognized to be of considerable technological as well as fundamental importance. Thus in the former category, a substantial number of important synthetic reactions for industrial purposes make use of metal surfaces as catalysts. Or again, problems of corrosion of metals are of great practical importance, such as in nuclear-reactor technology [see, for instance, my earlier articles, in: Physics Bulletin, Volume 25, p. 582, Institute of Physics, UK (1974); and in: Physics and Contemporqry Needs (Riazuddin, ed. ), Vol. 1, p. 53, Plenum Press, New York (1977)]. It is therefore of significance to strive to gain a more fundamental understand­ ing of the atomic, and ultimately the electronic, processes that occur when a molecule is brought into the proximity of a metal surface. The present volume focuses mainly on the theory and concepts involved; however, it is intended for readers in chemistry, physics, and materials science who are not specialists in theory but nevertheless wish to learn more about this truly interdisciplinary area of theoretical science. The aim of the book is to present the way in which valence theory can be synthesized with the understanding of metals that has been gained over the last half century or so. While advanced theory has at times been necessary, is largely presented in an extensive set of Appendixes.

This book deals with three related areas having both fundamental and technological interest. In the first part, the objective is to provide a bird's­ eye view on structure in polymeric solids. This is then complemented by a chapter, directly technological in its emphasis, dealing with the influence of processing on polymeric materials. In spite of the technological interest, this leads to some of the current fundamental theory. Part II, concerned with liquid crystals, starts with a discussion of the physics of the various types of material, and concludes with a treatment of optical applications. Again, aspects of the theory are stressed though this part is basically phenomenological in character. In Part III, an account is given first of the use of chemical-bonding arguments in understanding the electronic structure of low-dimensional solids, followed by a comprehensive treatment of the influence of dimen­ sionality on phase transitions. A brief summary of dielectric screening in low-dimensional solids follows. Space-charge layers are then treated, including semiconductor inversion layers. Effects of limited dimensionality on superconductivity are also emphasized. Part IV concludes the volume with two specialized topics: electronic structure of biopolymers, and topological defects and disordered systems. The Editors wish to acknowledge that this book had its origins in the material presented at a course organized by the International Centre for Theoretical Physics, Trieste.

The first Europhysics Study Conference on Electroweak Effects at High Energies was held at the "Ettore Majorana" Centre for Scientific Culture in Erice, Sicily from February 1 -12, 1983. The conference was attended by 61 physicists from 11 countries. The conference was sponsored by the European Physical Society, the Italian Ministry of Public Education, the Italian Ministry of Technological Research, the Sicilian Regional Government and the California Institute of Technology. CONFERENCE FORMAT The Study Conference followed a new intensive format in which the state of our knowledge of the electroweak interaction, and the relation of the electroweak sector to Grand Unified and Superunified Theories was reviewed in some depth. During the two week conference, 54 experimental and theoretical talks were presented, and four evening discussion sessions were held. The Erice surroundings, the wide-ranging conference program, and the fact that nearly all of the participants were directly involved in recent major experimental or theoretical developments, led to animated and very friendly discussions. Participants had the rare opportunity to view most of the major trends in high energy physics in a short interval of time, and to discuss and contemplate the trends in the uniquely peaceful yet stimulating atmosphere which is an Erice tradition.

One of the greatest advances in Geriatric Medicine during the last quarter of a century has been the increased realization of the possibilities of treatment for elderly patients. Neglect has been replaced by a more optimistic therapeutic endeavour and countless old people have benefitted from this approach. But there is also a drawback, and this is the risk of hazardous side effects of medication which are often directly proportional to the biological potency of the drug and may be unpredictably increased due to changes in the senile organism. In fact the anatomical and biological changes in old age alter both the kinetics of most drugs and the receptor response. On account of these changes the individual tolerance of aged patients to drug therapy may be quite different from that of younger subjects. Thus for a variety of reasons elderly patients receive more drugs, but they are at a higher risk of encountering adverse reactions, which often show atypical clinical features. We can therefore speak of "geriatric iatrogenic disorders" and point out that some of these side effects are determined by a complex pathogenesis due to the particular pathophysiological condition in the elderly. It is important to encourage the habit of individ­ ually evaluating potential risk versus expected advantages of drugs in keeping with the same principles adopted in the evaluation of cost/benefit ratio.

Although the problem of a metal in one dimension has long been known to solid-state physicists, it was not until the synthesis of real one-dimensional or quasi-one-dimensional systems that this subject began to attract considerable attention. This has been due in part to the search for high­ temperature superconductivity and the possibility of reaching this goal with quasi-one-dimensional substances. A period of intense activity began in 1973 with the report of a measurement of an apparently divergent conduc­ tivity peak in TfF-TCNQ. Since then a great deal has been learned about quasi-one-dimensional conductors. The emphasis now has shifted from trying to find materials of very high conductivity to the many interesting problems of physics and chemistry involved. But many questions remain open and are still under active investigation. This book gives a review of the experimental as well as theoretical progress made in this field over the last years. All the chapters have been written by scientists who have established themselves as experts in theoreti­ cal and experimental solid-state physics. The book is intended to be of use both to students and researchers entering the field as well as to more advanced physicists. The wealth of ideas and information it contains ought to be useful to anyone interested in quasi-one-dimensional systems, organic solids, or the search for novel conduction and superconduction mechanisms. The editors are very grateful to the authors for their collaboration in this book.

The authors' aim is to present a review of experimental and theoretical research that has been done to establish and to explain the physical properties of actinide compounds. The book is aimed at physicists and chemists. It was thought useful to collect a large selection of diagrams of experimental data scattered in the literature. Experiment and theory are presented separately, with cross­ references. Not all work has been included: rather, typical examples are discussed. We apologize to all researchers whose work has not been quoted. Since we report on an active field of research, clearly the data and their interpretation are subject to change. We benefitted greatly from discussions with many of our colleagues, particularly with Drs. G. H. Lander and W. Suski. The help of Mrs. C. Bovey and Ch. Lewis in the preparation of the manuscript, and the artwork and photo­ graphic work of Ms. Y. Magnenat and E. Spielmann of the Institute of Experi­ mental Physics of the University of Lausanne, are gratefully acknowledged. Our particular thanks are due to Ms. J. Ubby for her skillful and patient editorial work.

Since the introduction of quantum mechanics, the general theory of solid state physics has developed very rapidly. To date, a number of good textbooks on general solid state physics have been written. However, research in solid state physics has become highly specialized and undertaken in narrow fields. There is thus a great need for elementary textbooks that deal in detail with the study of solids in a particular field in order to give students basic knowledge in that field. Metallic solids with an impurity, generally called alloys, are of immense importance from both fundamental and technological points of view. The pioneering work of Bloember­ gen and Rowland (1953) gave considerable impetus to the study of the electronic structure of metallic alloys. Serious theoretical study in this field started in 1960 and, during the last two decades, considerable success in understanding the electronic structure of simple metal alloys has been achieved. Nonetheless the theoretical study of dilute alloys of transition metals is still in its infancy. At present there are few review articles and original research papers that examine the role of an impurity with respect to the electronic structure and properties of metallic alloys. Because of the absence of an elementary textbook that presents a comprehensive account of different aspects of the electronic structure of metallic alloys, I have written this elementary textbook on the theory of the electronic structure of metallic alloys.

A hundred and eighty five chemists, physicists, and engineers met in Schenectady, New York, for the three days May 10-12, 1976, to discuss the subject of Superionic Conductors. This International Conference was held at the Research and Development Center of the General Electric Company. The subject of the Conference was fast ion transport in solids. These materials have potential application in new types of batteries, fuel cells, and sensors. Some like beta alumina are under active development in nov'el new systems. Their study has also become a popular area of scientific investigation. One objective of the Conference was to provide a forum for interdisciplinary communication between chemists, physicists, and engineers. The Conference was an attempt to bring these groups together, in order to listen to each others problems and progress. We began organizing the Conference in the spring of 1975. It was suggested to General Electric managers Drs. Craig S. Tedmon, Jr. and Roland W. Schmitt. They provided immediate and enthusiastic support. They also provided the advice, staff, and backup which were necessary at all points in the planning and duration of the Conference. We were also pleased that they could participate in the Conference: Dr. Tedmon welcomed the participants and officially opened the Conference, and Dr. Schmitt gave the after banquet address. We thank them. Additional and invaluable help, and advice, were also provided by Drs. D. Chatterji, J. B. Bush, G. W. Ludwig, and J. B. Comly. We were joined on the program committee by Drs.

There is considerable interest, both fundamental and technological, in the way atoms and molecules interact with solid surfaces. Thus the description of heterogeneous catalysis and other surface reactions requires a detailed understand­ ing of molecule-surface interactions. The primary aim of this volume is to provide fairly broad coverage of atoms and molecules in interaction with a variety of solid surfaces at a level suitable for graduate students and research workers in condensed matter physics, chemical physics, and materials science. The book is intended for experimental workers with interests in basic theory and concepts and had its origins in a Spring College held at the International Centre for Theoretical Physics, Miramare, Trieste. Valuable background reading can be found in the graduate-Ievel introduction to the physics of solid surfaces by ZangwilI(1) and in the earlier works by Garcia­ Moliner and F1ores(2) and Somorjai.(3) For specifically molecule-surface interac­ tions, additional background can be found in Rhodin and Ertl(4) and March.(S) V. Bortolani N. H. March M. P. Tosi References 1. A. Zangwill, Physics at Surfaces, Cambridge University Press, Cambridge (1988). 2. F. Garcia-Moliner and F. Flores, Introduction to the Theory of Solid Surfaces, Cambridge University Press, Cambridge (1979). 3. G. A. Somorjai, Chemistry in Two Dimensions: Surfaces, Cornell University Press, Ithaca, New York (1981). 4. T. N. Rhodin and G. Erd, The Nature of the Surface Chemical Bond, North-Holland, Amsterdam (1979). 5. N. H. March, Chemical Bonds outside Metal Surfaces, Plenum Press, New York (1986).