Collision Theory And Statistical Theory Of Chemical Reactions

Since the discovery of quantum mechanics,more than fifty years ago,the theory of chemical reactivity has taken the first steps of its development. The knowledge of the electronic structure and the properties of atoms and molecules is the basis for an un derstanding of their interactions in the elementary act of any chemical process. The increasing information in this field during the last decades has stimulated the elaboration of the methods for evaluating the potential energy of the reacting systems as well as the creation of new methods for calculation of reaction probabili ties (or cross sections) and rate constants. An exact solution to these fundamental problems of theoretical chemistry based on quan tum mechanics and statistical physics, however, is still impossible even for the simplest chemical reactions. Therefore,different ap proximations have to be used in order to simplify one or the other side of the problem. At present, the basic approach in the theory of chemical reactivity consists in separating the motions of electrons and nu clei by making use of the Born-Oppenheimer adiabatic approximation to obtain electronic energy as an effective potential for nuclear motion. If the potential energy surface is known, one can calculate, in principle, the reaction probability for any given initial state of the system. The reaction rate is then obtained as an average of the reaction probabilities over all possible initial states of the reacting ~artic1es. In the different stages of this calculational scheme additional approximations are usually introduced.

This treatise is devoted to an analysis of the present state of the quantum theory of chemical reactions. It will be divided into three volumes and will contain the contributions to an international seminar organized by the editors. The first one, is concerned with the fundamental problems which occur when studying a gas phase reaction or a reaction for which the solvent effect is not taken into account. The two first papers show how the collision theory can be used to predict the behaviour of interacting small molecules. For large molecules the complete calculations are not possible. We can only estimate the reaction path by calculating important areas of the potential surfaces. Four papers are concerned with this important pro cess. Furthermore, in one of these, the electronic reorganization which occurs along the reaction path is carefully analyzed. ~~o papers are devoted to the discussion of general rules as aromaticity rules, symmetry rules. The last two papers are concerned with the electrostatic molecular poten tial method which is the modern way of using static indices to establish relations between structure and chemical reactivity. Volume II will be devoted to a detailed analysis of the role of the solvent and volume III will present important applications as reaction mechanisms, photochemistry, catalysis, biochemical reactions and drug design. SOME RECENT DEVELOPMENTS IN THE MOLECULAR TREATMENT OF ATOM-ATOM COLLISIONS.

Reaction Rate Theory and Rare Events bridges the historical gap between these subjects because the increasingly multidisciplinary nature of scientific research often requires an understanding of both reaction rate theory and the theory of other rare events. The book discusses collision theory, transition state theory, RRKM theory, catalysis, diffusion limited kinetics, mean first passage times, Kramers theory, Grote-Hynes theory, transition path theory, non-adiabatic reactions, electron transfer, and topics from reaction network analysis. It is an essential reference for students, professors and scientists who use reaction rate theory or the theory of rare events. In addition, the book discusses transition state search algorithms, tunneling corrections, transmission coefficients, microkinetic models, kinetic Monte Carlo, transition path sampling, and importance sampling methods. The unified treatment in this book explains why chemical reactions and other rare events, while having many common theoretical foundations, often require very different computational modeling strategies. Offers an integrated approach to all simulation theories and reaction network analysis, a unique approach not found elsewhere Gives algorithms in pseudocode for using molecular simulation and computational chemistry methods in studies of rare events Uses graphics and explicit examples to explain concepts Includes problem sets developed and tested in a course range from pen-and-paper theoretical problems, to computational exercises

This book deals with a central topic at the interface of chemistry and physics--the understanding of how the transformation of matter takes place at the atomic level. Building on the laws of physics, the book focuses on the theoretical framework for predicting the outcome of chemical reactions. The style is highly systematic with attention to basic concepts and clarity of presentation. The emphasis is on concepts and insights obtained via analytical theories rather than computational and numerical aspects. Molecular reaction dynamics is about the detailed atomic-level description of chemical reactions. Based on quantum mechanics and statistical mechanics, the dynamics of uni- and bi-molecular elementary reactions are described. The book features a comprehensive presentation of transition-state theory which plays an important role in practice, and a detailed discussion of basic theories of reaction dynamics in condensed phases. Examples and end-of-chapter problems are included in order to illustrate the theory and its connection to chemical problems. The second edition includes updated descriptions of adiabatic and non-adiabatic electron-nuclear dynamics, an expanded discussion of classical two-body models of chemical reactions, including the Langevin model, additional material on quantum tunnelling and its implementation in Transition-State Theory, and a more thorough description of the Born and Onsager models for solvation.

This treatise is devoted to an analysis of the present state of the quantum theory of chemical reactions. It will be divided into three volumes and will contain the contributions to an international seminar organized by the editors. The first one, is concerned with the fundamental problems which occur when studying a gas phase reaction or a reaction for which the solvent effect is not taken into account. The two first papers show how the collision theory can be used to predict the behaviour of interacting small molecules. For large molecules the complete calculations are not possible. We can only estimate the reaction path by calculating important areas of the potential surfaces. Four papers are concerned with this important pro cess. Furthermore, in one of these, the electronic reorganization which occurs along the reaction path is carefully analyzed. ~~o papers are devoted to the discussion of general rules as aromaticity rules, symmetry rules. The last two papers are concerned with the electrostatic molecular poten tial method which is the modern way of using static indices to establish relations between structure and chemical reactivity. Volume II will be devoted to a detailed analysis of the role of the solvent and volume III will present important applications as reaction mechanisms, photochemistry, catalysis, biochemical reactions and drug design. SOME RECENT DEVELOPMENTS IN THE MOLECULAR TREATMENT OF ATOM-ATOM COLLISIONS.

This book deals with a central topic at the interface of chemistry and physics - the understanding of how the transformation of matter takes place at the atomic level. Building on the laws of physics, the book focuses on the theoretical framework for predicting the outcome of chemical reactions. The style is highly systematic with attention to basic concepts and clarity of presentation. Molecular reaction dynamics is about the detailed atomic-level description of chemical reactions. Based on quantum mechanics and statistical mechanics or, as an approximation, classical mechanics, the dynamics of uni- and bi-molecular elementary reactions are described. The book features a detailed presentation of transition-state theory which plays an important role in practice, and a comprehensive discussion of basic theories of reaction dynamics in condensed phases. Examples and end-of-chapter problems are included in order to illustrate the theory and its connection to chemical problems.