Despite the fact that many years have elapsed since the first microcalorimetric measurements of an action potential were made, there is still among the research workers involved in the study of bioelectrogenesis a complete overlooking of the most fundamental principle governing any biological phenomenon at the molecular scale of dimension. This is surprising, the more so that the techniques of molecular biology are applied to characterize the proteins forming the ionic conducting sites in living membranes. For reasons that are still obscure to us the molecular aspects of bioelectrogenesis are completely out of the scope of the dynamic aspects of biochemistry. Even if it is sometimes recognized that an action potential is a free energy-consuming, entropy-producing process, the next question that should reasonably arise is never taken into consideration. There is indeed a complete evasion of the problem of biochemical energy coupling thus reducing the bioelectrogenesis to only physical interactions of membrane proteins with the electric field: the inbuilt postulate is that no molecular transformations, in the chemical sense, could be involved.

This volume contains a selection of scientific papers related to the structure and dynamics of non-rigid molecules. This frontline topic was born a few decades ago, when Longuet-Higgins proposed his famous theory of Molecular Symmetry Groups (Mol. Phys. 6, (1962) 457). Unfortunately, since this early paper, very few publications have been devoted to the study of non-rigid molecules. Let us mention some books which dedicate some chapters to them: Induced Representations in Crystals and Molecules, by S. L. Altmann, Academic Publishers, 1977; Molecular Symmetry and Spectroscopy, by P. R. Bunker, Academic Publishers, 1979; and finally Large Amplitude Motion in Molecules, Vols. I and II, by several authors, Springer Verlag, 1979. More recently an International Symposium on Non-Rigid Molecules was held in Paris, France, from 1-7 July 1982, the proceedings of which were published in the volume entitled Symmetries and Properties of Non-Rigid Molecules. A Comprehensive Survey, edited by J. Maruani et al., Elsevier, 1983. Finally, we should mention the very specialized work The Permutational Approach to Dynamic Stereochemistry, by J. Brocas et al., McGraw-Hill, 1983. The purpose of this book is to fill in this information on the structure and dynamics of non-rigid systems. To this aim, we have gathered a collection of recent papers written by the most qualified specialists in the world, covering a large field from van der Waals molecules to inorganic complexes and organic polyrotor molecules, as well as considering statistical and dynamic aspects.

At the time when increasing numbers of chemists are being attracted by the fascination of supposedly easy computing and associated colourful imaging, this book appears as a counterpoint. The first part focuses on fundamental concepts of quantum chemistry, covering MCSCF theory, perturbation treatments, basis set developments, density matrices, wave function instabilities to correlation effects, and momentum space theory. The second part is devoted to more practical studies, ranging from the characterisation of exotic interstellar molecules, the accurate determination of spectroscopic constants, excited states structures and EPR parameters through photochemical and charge-transfer processes, cluster chemistry and fullerenes, muonium chemistry, to the possible prediction of the response of materials to electric fields in view of nonlinear optical applications. Audience: Graduate students and researchers whose work involves quantum chemistry, molecular physics, and materials modelling.

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 present volume gathers a series of selected and updated contributions presented at the International Symposium on Applied Theoretical Chemistry held in Havana, Cuba, July 2-6, 1990. This Symposium was intended to illustrate current applications of Theoretical Chemistry in different fields of Physical Chemistry. Theoretical Chemistry has become a powerful tool of investigation in all areas of Chemistry, Biochemistry, and Physical Chemistry. The plenary lectures given in the Symposium were classified into four topics: Atom-Surface Interactions, Chemical Reaction Mechanisms, Molecular Structure and Properties, and Molecular Spectroscopy. We retain the same division in this volume. Over 60 scientists from Cuba, Finland, France, Germany, Great-Britain, Hungary, Italy, Spain, Sweden, USA, USSR, and Venezuela participated in the Conference. Twenty plenary lectures were given by distinguished members of the international scientific community. Furthermore, a large number of posters were presented by younger experts in various fields of Theoretical Chemistry. This International Symposium was organized by the Faculty of Chemistry of the University of Havana and the Cuban Chemical Society. It was an opportunity to bring together in Havana several outstanding scientists from various countries of the world. Havana is worldwide renown for its wonderful climate, the hospitality of its inhabitants, and the proximity of beautiful touring resorts.

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.

This book introduces the principles and concepts of chemical and biochemical sensors for analyzing medical as well as biological samples. For applications like analyzing or monitoring gastric juice or blood plasma, the potential of sensors is exceptionally large. Focussed on these applications, the interpretation of analytical results is explained. Specific advantages are compared to other analytical techniques. Numerous tables with data provide useful information not easily found elsewhere and make a handy source of reference. Ursula E. Spichiger-Keller is head of the Center for Chemical Sensors/Biosensors and Bioanalytical Chemistry at the Swiss Federal Institute of Technology (ETH) in Zurich.