Seven review articles and original papers provide a representative overview of the research work done in hydrogen bond research at Austrian universities. The topics covered by the contributions are: state-of-the-art of understanding hydrogen bonding in biopolymers; recent NMR techniques for studying hydrogen bonding in aqueous solutions; intramolecular hydrogen bonding and proton transfer in a class of Mannich bases derived from substituted phenols and naphthols; competition between intramolecular hydrogen bonds in ortho-disubstituted phenols; molecular dynamic simulations on proton transfer in 5,8-dihydroxynaphthoquinone and in the formic acid dimer; accurate calculations of the intermolecular interactions in cyanoacetylen dimers; correlation between OH...O bond distances and OH stretching frequencies as derived from structural and spectroscopic data of minerals.

André Julg has published several papers concerning the continuity of classical physics and quantum mechanics. He provides a provocative conclusion in this book: the quantum formalism can be effectively interpreted within the framework of classical physics, provided some minor rearrangements are accepted.

The linear Schrodinger equation is central to Quantum Chemistry. It is presented within the context of relativistic Quantum Mechanics and analysed both in time-dependent and time-independent forms. The Riccati equation is used to study the one-dimensional Schrodinger equation.
The authors develop the Schrodinger-Riccati equation as an approach to determine solutions of the time-independent, linear Schrodinger equation."

Development in science depends on several factors. Among these, the role of individual scientists is perhaps not the most important one. Science is typically a body of collective knowledge and any increase in the amount of this knowledge is certainly due to strong interaction among scientists. Even in the past, it happened quite rarely that a single person, without any aid of others, d- covered something fundamental or opened a new chapter in science. Great figures of science history have, in most cases, had rather a summarizing and s- thesizing role. This is especially valid over the last few decades. On one hand, the amount of information necessary to achieve new discoveries, has increased tremendously. On the other hand, improvement of technical facilities has increased the speed of information exchange. These factors resulted in a degree of specialization in science that had never seen before. Most of us are experts and specialists rather than scientists in the classical sense. My personal feeling is that, even nowadays, there is a strong need for professionals with a broad knowledge and c- prehensive mind, although they may not be competitive in the number of their publications or the sizes of their grants. Every time I have met such a person (I can count these cases on my fingers) I have become deeply influenced by his or her strong intellect.

The main subjects are:
- a comprehensive mathematical description of molecular systems,
- a new reaction path concept,
- an algorithm for following the reaction path.
The reaction path's tangent is determined by an excitation vector and the saddle points surrounding a minimizer can be localized without further information. A procedure appropriate to trace these reaction paths is presented.

This book is an outcome of the International Workshop on Electronic Density Functional Theory, held at Griffith University in Brisbane, Australia, in July 1996. Density functional theory, standing as it does at the boundary between the disciplines of physics, chemistry, and materials science, is a great mixer. Invited experts from North America, Europe, and Australia mingled with students from several disciplines, rapidly taking up the informal style for which Australia is famous. A list of participants is given at the end of the book. Density functional theory (DFT) is a subtle approach to the very difficult problem of predicting the behavior of many interacting particles. A major application is the study of many-electron systems. This was the workshop theme, embracing inter alia computational chemistry and condensed matter physics. DFT circumvents the more conceptually straightforward (but more computationally intensive) approach in which one solves the many-body Schrodinger equation. It relies instead on rather delicate considerations involving the electron number density. For many years the pioneering work of Kohn and Sham (the Local Density Ap proximation of 1965 and immediate extensions) represented the state of the art in DFT. This approach was widely used for its appealing simplicity and computability, but gave rather modest accuracy. In the last few years there has been a renaissance of interest, quite largely due to the remarkable success of the new generation of gradient functionals whose initiators include invitees to the workshop (Perdew, Parr, Yang)."

Quantum Systems in Chemistry and Physics contains a refereed selection of the papers presented at the first European Workshop on this subject, held at San Miniato, near Pisa, Italy, in April 1996. The Workshop brought together leading experts in theoretical chemistry and molecular physics with an interest in the quantum mechanical many-body problem. This volume provides an insight into the latest research in this increasingly important field. Throughout the Workshop, the emphasis was on innovative theory and conceptual developments rather than on computational implementation. The various contributions presented reflect this emphasis and embrace topics such as density matrices and density functional theory, relativistic formulations, electron correlation, valence theory, nuclear motion, response theory, condensed matter, and chemical reactions. Audience: The volume will be of interest to those working in the molecular sciences and to theoretical chemists and molecular physicists in particular.

The development of computational methods that support human health and environmental risk assessment of engineered nanomaterials (ENMs) has attracted great interest because the application of these methods enables us to fill existing experimental data gaps. However, considering the high degree of complexity and multifunctionality of ENMs, computational methods originally developed for regular chemicals cannot always be applied explicitly in nanotoxicology. This book discusses the current state of the art and future needs in the development of computational modeling techniques for nanotoxicology. It focuses on (i) computational chemistry (quantum mechanics, semi-empirical methods, density functional theory, molecular mechanics, molecular dynamics), (ii) nanochemoinformatic methods (quantitative structure-activity relationship modeling, grouping, read-across), and (iii) nanobioinformatic methods (genomics, transcriptomics, proteomics, metabolomics). It reviews methods of calculating molecular descriptors sufficient to characterize the structure of nanoparticles, specifies recent trends in the validation of computational methods, and discusses ways to cope with the uncertainty of predictions. In addition, it highlights the status quo and further challenges in the application of computational methods in regulation (e.g., REACH, OECD) and in industry for product development and optimization and the future directions for increasing acceptance of computational modeling for nanotoxicology.

A number of general-purpose, reasonably accurate and well-tested ab-initio codes for crystals are discussed in this book. The aim is to expand competence of their application in material sciences and solid-state physics. The book addresses particularly readers with a general knowledge in quantum chemistry and intends to give a deeper insight into the special algorithms and computational techniques in ab-initio computer codes for crystals. Three different programs which are available to all interested potential users on request are presented.

This volume contains the proceedings of the NATO Advanced Research Workshop on "Atomic and Molecular Wires". It was sponsored by the Ministry of Scientific Affairs Division special program on Nanoscale Science with the support of the CNRS and the Max Planck Institute. Scientists working or interested in the properties of wires at a subnanoscale were brought together in Les Houches (France) from 6 to 10 May 1996. Subnanoscale wires can be fabricated either by surface physicists (atomic wires) or by synthetic chemists (molecular wires). Both communities present their foremost advances using, for example, STM to assemble atomic lines atom for atom, to fabricate a mask for such a line or using the wide range of chemical synthesis techniques to obtain long, rigid and conjugated oligomers. Interconnecting such tiny wires to sources (voltage, current) continues to demand a great technological effort. But nanolithography associated with microfabrication or STM are now clearly identified paths for measuring the electrical resistance of an atomic or a molecular wire. The first measurements have been reported on Xe , benzene, C ' di(phenylene-ethynylene) showing 2 60 the need for a deeper understanding of transport phenomena through subnanowires. Such transport phenomena like tunnel (off-resonance) transport and Coulomb blockade have been discussed by theorists with an emphasis on the exponential decrease of the tunnel current with the wire length versus the ballistic regime of transport.

Our understanding of the quantitative aspects of free radical chemistry and the involvement of radicals in such areas as biology, medicine, the environment, etc., has developed spectacularly over recent years, yet the various topics are commonly discussed separately, in specific meetings and specialised publications. Free Radicals in Biology and Environment draws together two important areas of free radical chemistry, using as a bridge the fundamental physical chemistry of free radicals (spectroscopic detection of free radicals, evaluation of absolute rate constants, elucidation of mechanisms of free radical reactions and catalysis, photochemical and radiation processes, etc.). The most relevant topics covered are the EPR detection of radicals in biochemical systems and in pollutant formation and degradation, oxidation processes in biology and in the troposphere, radiation and induced damage, and atmospheric pollutants arising from incomplete combustion. Also covered are the chemistry and biochemistry of nitric oxide and peroxynitrite, the chemistry and biochemistry of DNA radicals, the role of radicals in myeloperoxidase, lignineperoxidase, radicals and cardiovascular injury, radiation and the fragmentation of cells and tissues.

This book gathers original contributions from a selected group of distinguished researchers that are actively working in the theory and practical applications of solvent effects and chemical reactions. The importance of getting a good understanding of surrounding media effects on chemical reacting system is difficult to overestimate. Applications go from condensed phase chemistry, biochemical reactions in vitro to biological systems in vivo. Catalysis is a phenomenon produced by a particular system interacting with the reacting subsystem. The result may be an increment of the chemical rate or sometimes a decreased one. At the bottom, catalytic sources can be characterized as a special kind of surrounding medium effect. The materials involving in catalysis may range from inorganic components as in zeolites, homogenous components, enzymes, catalytic antibodies, and ceramic materials. . With the enormous progress achieved by computing technology, an increasing number of models and phenomenological approaches are being used to describe the effects of a given surrounding medium on the electronic properties of selected subsystem. A number of quantum chemical methods and programs, currently applied to calculate in vacuum systems, have been supplemented with a variety of model representations. With the increasing number of methodologies applied to this important field, it is becoming more and more difficult for non-specialist to cope with theoretical developments and extended applications. For this and other reasons, it is was deemed timely to produce a book where methodology and applications were analyzed and reviewed by leading experts in the field.

Molecular similarity has always been an important conceptual tool of chemists, yet systematic approaches to molecular similarity problems have only recently been recognized as a major contributor to our understanding of molecular properties. Advanced approaches to molecular similarity analysis have their foundation in quantum similarity measures, and are important direct or indirect contributors to some of the predictive theoretical, computational, and also experimental methods of modern chemistry. This volume provides a survey of the foundations and the contemporary mathematical and computational methodologies of molecular similarity approaches, where special emphasis is given to applications of similarity studies to a range of practical and industrially significant fields, such as pharmaceutical drug design. The authors of individual chapters are leading experts in various sub-fields of molecular similarity analysis and the related fundamental theoretical chemistry topics, as well as the relevant computational and experimental methodologies. Whereas in each chapter the emphasis is placed on a different area, nevertheless, the overall coverage and the wide scope of the book provides the reader with a general yet sufficiently detailed description that may serve as a good starting point for new studies and applications of molecular similarity approaches. The editors of this volume are grateful to the authors for their contributions, and hope that the readers will find this book a useful and motivating source of information in the rapidly growing field of molecular similarity analysis.

Supramolecular stereochemistry is a topic with enormous breadth, and this book brings together experts in polymer chemistry, bioorganic chemistry, crystallography, materials science, dendrimer science, nanochemistry, conformational analysis, molecular recognition chemistry, and topological stereochemistry. Contains 19 plenary and 12 poster contributions.

The first volume of Lecture Notes in Quantum Chemistry (Lecture Notes in Chemistry 58, Springer Verlag, Berlin 1992) contained a compilation of selected lectures given at the two first European Summer Schools in Quantum Chemistry (ESQC), held in southern Sweden in August 1989 and 1991, respectively. The notes were written by the teachers at the school and covered a large range of topics in ab initio quantum chemistry. After the third summer school (held in 1993) it was decided to put together a second volume with additional material. Important lecture material was excluded in the first volume and has now been added. Such added topics are: integrals and integral derivatives, SCF theory, coupled-cluster theory, relativity in quantum chemistry, and density functional theory. One chapter in the present volume contains the exercise material used at the summer school and in addition solutions to all the exercises. It is the hope of the authors that the two volumes will find good use in the scientific community as textbooks for students, who are interested in learn ing more about modern methodology in molecular quantum chemistry. The books will be used as teaching material in the European Summer Schools in Quantum Chemistry, which are presently planned. Lund in July 1994 Bjorn Roos NOTES ON HARTREE-FOCK THEORY AND RELATED TOPICS JanAlmlof Department of Chemistry University of Minnesota Minneapolis, MN 55455. USA Contents: 1 * Introduction. 2 . The Born-Oppenheimer Approximation. 3. Determinant Wavefunctions and the Pauli Principle. 4. Expectation Values With a Determinant Wavefunction.

In the study of various phenomena in nature, the concept of similarity plays a fundamental role. Chemistry is no exception; the similarity of molecules, both in their physical properties and in their chemical reactions, provides a basis for their classification, characterization, and scientific description. Ultimately, the recognition and analysis of molecular similarities serve as the basis of an understanding of molecular structures and properties, and rep resent the first steps in the development of theoretical models explaining chemical behavior. In this role, molecular similarity is the foundation of predictive models in chemistry. Molecular similarity and molecular reactivity are strongly related. Studying the reactivities of molecules is an important tool for detecting molecular similarities and differences; alternatively, similar molecular properties often imply similar reactivities. This latter aspect is of special value, allowing chemists to make predictions concerning the outcomes of chemical reactions based on molecular similarities. In this book, the central theme, molecular similarity, is discussed from a variety of viewpoints covering the range from rigorous quantum chemical approaches to phenomenological observations expressed within appropriate physical and mathematical frameworks. The authors of the various chapters represent some of the most current fields of research on molecular similarity. It is the hope of the editor that by bringing these subjects together under the cover of this book will provide the readers with a broad perspective and a handy reference of the contemporary approaches to similarity analysis of molecules and reactions."

Chemical bonds, their intrinsic energies in ground-state molecules and the energies required for their actual cleavage are the subject of this book. The theory, modelled after a description of valence electrons in isolated atoms, explains how intrinsic bond energies depend on the amount of electronic charge carried by the bond-forming atoms. It also explains how bond dissociation depends on these charges. While this theory vividly explains thermochemical stability, future research could benefit from a better understanding of bond dissociation: if we learn how the environment of a molecule affects its charges, we also learn how it modifies bond dissociation in that molecule. This essay is aimed at theoretical and physical-organic chemists who are looking for new perspectives to old problems.

The title of this volume implies a progression of sorts from species of molecular size to a product described on the basis of continuum prop erties. The difference in approach from the standpoint of molecular be havior, on the one hand-more the forte of chemists-and from the standpoint of large-scale properties, on the other-more the province of chemical engineers and materials scientists-represents a severe cultural divide, but one with much potential for creative input from both sides. Chapter 1 of this volume attempts a broad survey of trends toward the synthesis of large, well-defined molecular systems with interesting physical, chemical, or material properties. Review articles with more de tailed treatments are emphasized. In Chapter 2, Newkome and Moore field summarize work on synthesis of /I cascade" molecules. Next, Denti, Campagna, and Balzani describe the synthesis of assemblies with con nected metal-containing chromophore units which transmit electrons or electronic energy in defined ways. In Chapter 4 Wuest describes the con struction of hydrogen-bonded organic networks, and in Chapter 5 Michl defines a molecular-level construction set. Finally, Jaszczak points out how nature's attempts over geological time spans are emulated by recent human synthetic activity in the fullerene arena, through the appearance of various morphologies of natural graphite. The book concludes with a method for describing fractal-like mole cules, and an index based on the method for appropriate compounds described in the text."

This book provides an introduction to the use of algebraic methods and sym bolic computation for simple quantum systems with applications to large order perturbation theory. It is the first book to integrate Lie algebras, algebraic perturbation theory and symbolic computation in a form suitable for students and researchers in theoretical and computational chemistry and is conveniently divided into two parts. The first part, Chapters 1 to 6, provides a pedagogical introduction to the important Lie algebras so(3), so(2,1), so(4) and so(4,2) needed for the study of simple quantum systems such as the D-dimensional hydrogen atom and harmonic oscillator. This material is suitable for advanced undergraduate and beginning graduate students. Of particular importance is the use of so(2,1) in Chapter 4 as a spectrum generating algebra for several important systems such as the non-relativistic hydrogen atom and the relativistic Klein-Gordon and Dirac equations. This approach provides an interesting and important alternative to the usual textbook approach using series solutions of differential equations."

The technique of smal1-angle soattering (SAS) is now about sixty years o1d. Soon after the first observations of, a continuous, intense X-ray scattering near the primary beam from samp1es such as canbo:tt,bla:cks, it was recognized that this scattering arose from e1ectron density heterogeneities on a scale of severa! tens to severa! hundred times the wave1ength of the radiation used. By the time the classic monograph of Guinier and Foumet appeared in 1955, much of the basic theory and instrumentation had been developed, and applications to colloidal suspensions, macromolecular solutions inc1uding proteins and viruses, fibers, porous and finely divided solids, metallic alloys etc. numbered in the hundreds. Following severa! specialized meetings, the first international conference on small-ang1e X-ray scattering was helditi, Syracuse in 1965, marked by the presentation of new scattering theory for polydisperse systems, polymer coils and filaments, new instrumentation (the Bonse-Hart camera), and new applications to polymeric, biologica!, and metallic systems, to critica! phenomena and to catalysts. The second conference (Graz, 1970) no longer dealt exclusively with X- ray scattering, but also inc1uded neutron small-angle scattering (SANS). SANS applications developed rapidly during this period, especially for studying synthetic and biologica! macromolecules, when the possibilities of exploiting scattering Iength density differences, created by selective deuteration, were recognized.

The progress in computer technology during the last 10-15 years has enabled the performance of ever more precise quantum mechanical calculations related to structure and interactions of chemical compounds. However, the qualitative models relating electronic structure to molecular geometry have not progressed at the same pace. There is a continuing need in chemistry for simple concepts and qualitatively clear pictures that are also quantitatively comparable to ab initio quantum chemical calculations. Topological methods and, more specifically, graph theory as a fixed-point topology, provide in principle a chance to fill this gap. With its more than 100 years of applications to chemistry, graph theory has proven to be of vital importance as the most natural language of chemistry. The explosive development of chemical graph theory during the last 20 years has increasingly overlapped with quantum chemistry. Besides contributing to the solution of various problems in theoretical chemistry, this development indicates that topology is an underlying principle that explains the success of quantum mechanics and goes beyond it, thus promising to bear more fruit in the future.

MICHAEL T. POPE AND ACHIM MULLER Department of Chemistry, Georgetown University, Washington, DC 20057-2222, U.S.A.; Department of Chemistry, University of Bielefeld, D-4BOO Bielefeld 1, F.R.G. Polyoxometalates, from their discovery and early development in the final decades of the 19th century to their current significance in disciplines as diverse as chemistry, mathematics, and medicine, continue to display surprisingly novel structures, unexpected reactivities and applications, and to attract increasing attention worldwide. Most of the contributors to the present volume participated in the workshop held at the Center for Interdisciplinary Research at the University of Bielefeld, July 15-17, 1992. The choice of topics illustrates some of the variety of directions and fields in which polyoxometalates can play an important role. Although many of the leading polyoxometalate research groups are represented here, we regret that time constraints, financial limitations, and in some cases difficulties of communication did not allow us to include significant and imp- tant work from other groups outside Europe and North America. In the following we briefly review the current status of the field of po- oxometalates.

The Twenty Sixth Jerusalem Symposium reflected the high standards of these distinguished scientific meetings, which convene once a year at the Israel Academy of Sciences and Humanities in Jerusalem to discuss a specific topic in the broad area of quantum chemistry and biochemistry. The topic at this year's Jerusalem Symposium was reaction dynamics in clusters and condensed phases, which constitutes a truly interdisciplinary subject of central interest in the areas of chemical dynamics, kinetics, photochemistry and condensed matter chemical physics. The main theme of the Symposium was built around the exploration of the interrelationship between the dynamics in large finite clusters and in infinite bulk systems. The main issues addressed microscopic and macroscopic sol vation phenomena, cluster and bulk spectroscopy, photodissociation and vibrational predissociation, cage effects, interphase dynamics, reaction dynamics and energy transfer in clusters, dense fluids, liquids, solids and biophysical systems. The interdisciplinary nature of this research area was deliberated by intensive and extensive interactions between modern theory and advanced experimental methods. This volume provides a record of the invited lectures at the Symposium.

Impressive advances have been made in the study of atomic structures, at both the experimental and theoretical levels. And yet, the scarcity of information on atomic energy levels is evident At the same time there exists a need for data, because of the developments in such diverse fields as astrophysics and plasma and laser research, all of them of fundamental importance as well as practical impact. This project of research in atomic structure, consisting of three components (formulation, computer program, and numerical results), constitutes a basic and comprehensive work with a variety of uses. In its most practical application, it will yield a rather accurate prediction of the energy levels of any atomic system, of use per se or in the interpretation and confirmation of experimental results. On the other hand, it will also be of use in the comparative study of the appropriateness of the various levels of approximation and as a point of reference.