Y.G. Smeyers 
Structure and Dynamics of Non-Rigid Molecular Systems 

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., Mc Graw-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.