Structure and Dynamics of Atoms and Molecules: Conceptual Trends, Softcover reprint of the original 1st ed. 1995

The rivers run into the sea, yet the sea is not full Ecclesiastes What is quantum chemistry? The straightforward answer is that it is what quan­ tum chemists do. But it must be admitted, that in contrast to physicists and chemists, "quantum chemists" seem to be a rather ill-defined category of scientists. Quantum chemists are more or less physicists (basically theoreticians), more or less chemists, and by and large, computationists. But first and foremost, we, quantum chemists, are conscious beings. We may safely guess that quantum chemistry was one of the first areas in the natural sciences to lie on the boundaries of many disciplines. We may certainly claim that quantum chemists were the first to use computers for really large scale calculations. The scope of the problems which quantum chemistry wishes to answer and which, by its unique nature, only quantum chemistry can answer is growing daily. Retrospectively we may guess that many of those problems meet a daily need, or are say, technical in some sense. The rest are fundamental or conceptual. The daily life of most quantum chemists is usually filled with grasping the more or less technical problems. But it is at least as important to devote some time to the other kind of problems whose solution will open up new perspectives for both quantum chemistry itself and for the natural sciences in general.

Elements of Hydrogen Transfer Theory.- 1. Introduction.- 2. One-Dimensional Tunneling.- 3. Spectroscopic Splittings.- 4. From Quantum Beats to Relaxation.- 5. Calculation of Relaxation Rates.- References.- Building a Bridge Between Ab Initio and Semiempirical Theories of Molecular Electronic Structure.- 1. Introduction.- 2. Theoretical Bridge Between Ab Initio and Semiempirical Methods.- 3. The Ab Initio HV Method.- 4. Ab Initio Computations of Correlated Semiempirical-Like Integrals.- 5. Acknowledgment.- 6. References.- Electron Delocalization in The Theory of Intermolecular and Intergroup Interactions: Cause, Effect, Prevention.- 1. Introduction.- 2. Unphysical States.- 3. Separability and Localizability of Electronic Wave Functions.- 4. Level Shift Operators.- 5. Hartree-Fock Approximation.- 6. Correspondences and Extensions.- Appendix A.- References.- Quantum Dynamics of Diatoms in External Fields.- 1. Introduction.- 2. The Hamiltonian.- 3. Quantum Time Evolution.- 4. Multiphoton Absorption in Hydrogen Fluoride.- 5. Laser Assisted Dynamics in Boron Hydride.- 6. Conclusions.- References.- Dimensional Scaling in Quantum Theory.- 1. Introduction.- 2. The Jacobian Weighting Factor.- 3. The Large-D Limit.- 4. Three-Particle Systems.- 5. An Atom-to-Molecule Transformation.- 6. N-Particle Systems.- 7. Discussion.- Acknowledgements.- References.- Probing The Collective and Independent-Particle Character of Atomic Electrons.- 1. Introduction.- 2. Symmetry-Based Interpretation.- 3. Interpretations Based on Wave Functions.- 4. Interpretations Based on Classical and Semiclassical Models.- 5. Summary and Conclusions.- References.- Electronic Structure Models: Computations, Chemical Insights and Appropriateness.- 1. Introduction.- 2. Model Hamiltonians.- 3. Response Properties, Wave Functions, and Levels of Theory.- 4. Example: The Frequency Dependent Hyperpolarizabilities of Push Pull Substituted Aromatics.- References.- The Work Formalism: A New Theory of Electronic Structure.- 1. Introduction.- 2. The Work Formalism.- 3. Comparisons with Other Local Potential Theories.- 4. Results of Application to Atoms.- 5. Conclusions and Future Work.- References.

This volume focuses on important conceptual trends in atomic and molecular theory.