Recently, the molecular structures of a relatively large number of sulphone compounds have been elucidated in the vapour phase by electron diffraction and microwave spectroscopy. The main purpose of these studies is the determination of the sulphur bond configuration and the conformational properties. This leads to the observation and correlation of characteristic structural variations as various ligands are attached to the S02 group and as comparisons are made with related molecules. Today it may be said that the structure of sulphone molecules is relatively well studied, and it appeared...

In this volume, for the first time, a dozen of papers is collected dealing with almost all important aspects of ion cyclotron resonance spectrometry. The ICR technique was developed very rapidly in the last two decades. It seems to the editors that the method is now established well enough to dedicate a progress report to it. This report is devided into three parts: The first articles pre- sent new developments in the theory of ICR spectrometry. They are fol~ lowed by papers on r.ecent developments of the experimental technique. About half of the volume is dedicated to applications of ICR...

Traditionally, when one deals with crystals, the first property to be presented is the periodicity of the lattice, and all methods of study are based on this characteristic, which is considered essential. In fact, crystals differ from the molecules of finite size that are studied in chemistry, only in their extremely large number of particles. Furthermore, the existence of faces, which limit the spread of crystals in space, necessarily breaks the periodicity of the system. For these reasons it is natural to apply to crystals the concepts and methods that have been widely tested in the study...

1. 1 STATEMENT OF THE PROBLEM Quantum chemistry judged not from the ever present possibility of unex- pected developments but on the basis of the achievements in the last fifty years, is predominantly limited to attempts to solve for the energy and expectation values of wave functions representing, in the limit, an exact solution to the Schroedinger equation. Because of well-known dif- ficulties in system with more than about 50 electrons, the adopted ap- proximations are generally rather crude. As examples of quantum chemical approximations we mention the total or partial neglects of...

The aim of these notes is to offer a modern picture of the pertur- bative approach to the calculation of intermolecular forces. The point of view taken is that a perturbative series truncated at a low order can provide a valuable way for valuating interaction energies, especial- ly if one limits oneself to the case of intermediate- and long-range distances between the interacting partners. Although the situation corresponding to short distances is essen- tially left out from our presentation, the problems which are within the range of the theory form a vast and important class: a large var-...

The aim of this chapter is to discuss in detail the Monte Carlo algorithms developed to compute the sequence distributions in polymers. Because stereoregular polymers constitute a unique form of copolymer, the stereosequence distributions in vinyl homopolymers and the sequence distributions in copolymers can be computed using the same algorithms. Also included is a brief review of probabilistic models (i. e. , Bernoulli trials and Markov chains) frequently used to compute the sequence distribtuion. The determination of sequence distributions is important for the under- standing of polymer...

The aIm of the present article is to give a critical exposition of the theory of the symmetry properties of rigid and nonrigid molecules. Despite the fact that several accounts of the subject, both technical and didactic, are now available, and despite the extensive discussion of nonrigid molecule symmetry that has been going on since the classic papers of Hougen and Longuet-Higgins, there remains a need for a unifying survey of the problem. Previous treatments have tended to emphasize one or the other particular viewpoint at the expense of a broader view. Renewed interest in the details of...

In this volume 28 papers are presented. They cover all the fields studied with ion cyclotron resonance today, including reviews on important fields as well as short contributions on special topics. This report is devided into four parts: 1. Detailed studies on simple molecules, 2. Systematic studies of the ion chemistry, 3. Spectrometer development and 4. Theory. The plan to edit a progress report of the complete field was projected at the 2nd International Symposium on Ion Cyclotron Resonance Spectrometry, held at the Akademie der Wissenschaften und der Literatur, Mainz, March, 1981. Most of...

Most of the properties of a metal-electrolyte interface, even the spe- cific nature of an electrode reaction, proneness of a metal to cor- rosion, etc., are primarily determined by the electrical double layer (EDL) at this boundary. It is therefore no surprise that for the last, at least, one hundred years intent attention should have been centered on EDL. So much of material has been gathered to date that we are easi- ly lost in this maze of information. A substantial part of the attempts to systematize these facts is made at present within the framework of thermodynamics. Such a confined...

The bond diagrammatic representation of molecules is the foundation of MOVB theory. To a certain extent, this kind of representation is analogous to the one on which "resonance theory" is based and this fact can be projected by a comparison of the various ways in which MOVB theory depicts a species made up of three core and two ligand MO's which define two subsystems containing a total of six electrons and the ways in which "resonance theory" (i. e., qualitative VB theory) depicts a six-electron-six-AO species such as the pi system of CH =CH-CH=CH-CH=O. The 2 different pictorial...