Elementary Methods of Molecular Quantum Mechanics shows the methods of molecular quantum mechanics for graduate University students of Chemistry and Physics. This readable book teaches in detail the mathematical methods needed to do working applications in molecular quantum mechanics, as a preliminary step before using commercial programmes doing quantum chemistry calculations.This book aims to bridge the gap between the classic Coulson's Valence, where application of wave mechanical principles to valence theory is presented in a fully non-mathematical way, and McWeeny's Methods of Molecular Quantum Mechanics, where recent advances in the application of quantum mechanical methods to molecular problems are presented at a research level in a full mathematical way. Many examples and mathematical points are given as problems at the end of each chapter, with a hint for their solution. Solutions are then worked out in detail in the last section of each Chapter.* Uses clear and simplified examples to demonstrate the methods of molecular quantum mechanics * Simplifies all mathematical formulae for the reader* Provides educational training in basic methodology

The second edition of Elementary Molecular Quantum Mechanics shows the methods of molecular quantum mechanics for graduate University students of Chemistry and Physics. This readable book teaches in detail the mathematical methods needed to do working applications in molecular quantum mechanics, as a preliminary step before using commercial programmes doing quantum chemistry calculations.This book aims to bridge the gap between the classic Coulson's Valence, where application of wave mechanical principles to valence theory is presented in a fully non-mathematical way, and McWeeny's Methods of Molecular Quantum Mechanics, where recent advances in the application of quantum mechanical methods to molecular problems are presented at a research level in a full mathematical way. Many examples and mathematical points are given as problems at the end of each chapter, with a hint for their solution. Solutions are then worked out in detail in the last section of each Chapter. - Uses clear and simplified examples to demonstrate the methods of molecular quantum mechanics - Simplifies all mathematical formulae for the reader - Provides educational training in basic methodology

Methods of Molecular Quantum Mechanics This advanced text introduces to the advanced undergraduate and graduate student the mathematical foundations of the methods needed to carry out practical applications in electronic molecular quantum mechanics, a necessary preliminary step before using commercial programmes to carry out quantum chemistry calculations. Major features of the book include: Consistent use of the system of atomic units, essential for simplifying all mathematical formulae Introductory use of density matrix techniques for interpreting properties of many-body systems An introduction to valence bond methods with an explanation of the origin of the chemical bond A unified presentation of basic elements of atomic and molecular interactions The book is intended for advanced undergraduate and first-year graduate students in chemical physics, theoretical and quantum chemistry. In addition, it is relevant to students from physics and from engineering sub-disciplines such as chemical engineering and materials sciences.

The last twenty years have seen remarkable advances in molecular quantum mechanics. The traditional methods expounded in the first successful edition of this book have been implemented on a grand scale. In the Second Edition, McWeeny has completely revised the text and has added a wealth of new material and example problems. Key Features * Self-contained development of modern quantum theory of molecular electronic structure and properties * Assumes only an elementary quantum mechanics background * Mathematical methods (vector spaces, representations, group theory, etc.) built up as required * Latest advances (use of second quantization, unitary group, propagators all developed assuming no previous knowledge)

This text unravels those fundamental physical principles which explain how all matter behaves. It takes us from the foundations of quantum mechanics, through quantum models of atomic, molecular, and electronic structure, and on to discussions of spectroscopy, and the electronic and magnetic properties of molecules.

Since this book was first published 20 years ago, there have been remarkable advances in molecular quantum mechanics. The traditional methods expounded in the first edition have been absorbed into thegrowing field of "computational chemistry": but the whole fabric of the subject has also changed under the impact of techniques originating in theoretical physics. Consequently, besides rewriting much of the original text, it has been necessary to add an almost equal amount of completely new material: this covers second quantization and diagrammatic perturbation theory,symmetric and unitary group methods, new forms of valence bond theory, dynamic properties and response, propagator and equation-of-motiontechniques and the theory of intermolecular forces. Problems (withhints on solutions) appear at the end of each chapter and form a valuable supplement to the text. Like the first edition, this is a "teaching book" which follows a deductive step-by-step path from basic principles up to the current frontiers of research. Although aimed primarily at graduate students and their teachers, it should be standard reference for all who come in contact with modern theories of the electronic structure and properties of molecules. The last twenty years have seen remarkable advances in molecular quantum mechanics. The traditional methods expounded in the first successful edition of this book have been implemented on a grand scale. In the Second Edition, Mcweeny has completly revised the text and has added a wealth of new material and example problems.

Molecular Quantum Mechanics, an accessible introduction to the foundations of quantum chemistry, established itself as a classic as soon as the original best-selling edition appeared. This new third edition will ensure its place is maintained in the forefront of its field. Entirely rewritten to present the subject more clearly than ever before, this new edition includes two completely new chapters - one on computational techniques in quantum chemistry, and another on scattering theory. Most of the material on the calculations of electronic structure is entirely new,and the discussions in the second edition have been enhanced with more mathematical rigour. With 330 two-colour illustrations, numerous worked examples, in-text exercises, an extensive further information section, and a wide range of applications treated consistently, this will surely prove to be an invaluable book for all senior chemistry undergraduates.

Introduction 1 1. 2. Basic Concepts and Phenomenological Description 6 2.1. Separation of the Center-of-Mass Motion 8 2.2. Separation of Electronic and Nuclear Motions. Interaction Potentials (Potential-Energy Surfaces) 11 2.2.1. Heuristic Considerations 11 2.2.2. Born-Oppenheimer Separation. Adiabatic Approximation, 16 Present State of Potential-Energy-Burface 2.2.3. Calculations 23 2.3. Scattering Channels 6 2.4. Classification of Elementary Processes. Microscopic Mechanism 27 D.ynamics of Atomic and Molecular Collisions: 3. Electronically Adiabatic Processes 32 Classical Approach 3.1. 33 Some Arguments for the Reliability of the Classical Approach 33 Atom-Atom Collisions. Elastic Scattering 34 Quasiclassical Treatment of Elementary Processes in Triatomic Systems: Inelastic and Reactive Scattering 44 IV Examples of Results of Trajectory Calculations 59 3.1.4. 64 Elements of Quantum-Mechanical Methods 3.2. Correspondence of Classical and Quantum- 3.2.1. 64 Mechanical Theories Time-Dependent Scattering Theory 71 3.2.2. Stationary Scattering Theory 77 3.2.3. One-Dimensional Scattering 78 3.2.3.1 - Three-Dimensional Elastic Scattering 83 3.2.3.2. Rearrangement Scattering (Reactions) 85 3.2.3.3. Examples of Quantum-Mechanical Calculations 3.2.4.