The current volume in the series, "Vibrational Spectra and Structure, "is a single topic volume on gas phase structural parameters. The title of the volume, "Equilibrium Structural Parameters," covers the two most common techniques for obtaining gas phase structural parameters: microwave spectroscopy and the electron diffraction technique. Since the quantum chemical method provides equilibrium geometries, the volume is an attempt to provide a connection between the experimental and theoretical parameters. The book provides a review on molecular structure determinations from spectroscopic data using scaled moments of inertia. The limited number of molecules for which equilibrium parameters have been obtained and the requirement of a large number of microwave data needed to obtain the equilibrium structural parameters is noted. Electron diffraction technique is reviewed, along with a description of how this can incorporate structural information from microwave spectroscopy, vibrational spectroscopy, or theoretical calculations to improve the determination of the structural parameters by electron diffraction studies. Also discussed are the theory and methods of microwave spectroscopy, describing in some detail ro and rs structures as well as rm structures and corrections based on "ab initio" calculations. The accuracy of the molecular geometry predictions by quantum chemical methods is considered in some detail with data presented in graphic rather than tabular form. This makes it possible to readily note the difference in the parameters predicted at the various levels of quantum mechanical calculations. The four authors have provided a coherent description of the various structural parameters obtained experimentally along with treatments needed to extract equilibrium bond distances and angles.

The current volume in the series "Vibrational Spectra and Structure" is a single topic volume on the vibrational spectra of molecules containing silicon in the solid state. "Molecular Approaches to Solids" has been treated by the workers in the Institute for Silicate Chemistry of the Russian Academy of Science in St. Petersburg for the past two decades. In the last 15 years, a number of publications have originated from the laboratory where quantum mechanical computations for suitably selected molecules have been utilized to explain the origins of some structure bonding interrelationships and silicates and to evaluate their force constants.

Since most of the developments in this area have been published in the Russian literature they remain relatively inaccessible to the Western scientists. This volume is a compilation of many of these publications and summarizes the essential conclusions of these studies.

Unfortunately, Professor Lazarev passed away after he had submitted the volume for publication.