Applications of electronic structure theory

1. A Priori Geometry Predictions.- 1. Introduction.- 2. Equilibrium Geometries by Hartree-Fock Theory.- 2.1. Restricted and Unrestricted Hartree-Fock Theories.- 2.2. Basis Sets for Hartree-Fock Studies.- 2.3. Hartree-Fock Structures for Small Molecules.- 2.4. Hartree-Fock Structures for Larger Molecules.- 3. Equilibrium Geometries with Correlation.- 4. Predictive Structures for Radicals and Cations.- 5. Conclusions.- References.- 2. Barriers to Rotation and Inversion.- 1. Introduction.- 1.1. Relation to Other Chapters in Volumes 3 and 4.- 1.2. Other Reviews.- 1.3. Historical Notes.- 2. Assessment of Computational Methods.- 2.1. The Correlation Energy.- 2.2. Survey of Recent Barrier Calculations.- 2.3. Geometry Optimization and Vibronic Coupling.- 2.4. Discussion of Tabulated Barrier Calculations.- 2.5. Extension to Large Molecules.- 3. Methods for Analyzing Rotational Barrier Mechanisms.- 3.1. Bond Orbitals and Localized Orbitals.- 3.2. N-Center Energy Partitions.- 3.3. Fourier Analysis.- 3.4. Energy Components.- 3.5. Hellmann-Feynman Theorems.- 3.6. Charge Distributions.- 4. Semiempirical Models.- 4.1. Orbital Interaction Models.- 4.2. Dominant Orbital Theories and Walsh-Mulliken Diagrams..- 4.3. Empirical Potentials.- References.- 3. Hydrogen Bonding and Donor-Acceptor Interactions.- 1 Introduction.- 2. Theoretical Methods.- 2.1. Ab Initio Methods for Studying H-Bond Potential Surfaces.- 2.2. Methods for Evaluating the H-Bond Energy Components.- 3. Observable Properties of Hydrogen-Bonded and Other Donor-Acceptor Complexes.- 3.1. Structure and Binding Energy.- 3.2. Spectroscopic Properties.- 3.3. Summary.- 4. Generalizations about the Hydrogen Bond.- 4.1. H-Bond Structure.- 4.2. Contributions to the H-Bond Energy.- 4.3. Charge Redistribution and Charge Transfer.- 4.4. The Inductive Effect on H Bonds and Proton Affinities.- 4.5. What Makes a Hydrogen Bond Unique?.- 4.6. The Impact of the Ab Initio Calculations on Semiempirical and Model Calculations.- 5. Summary.- References.- 4. Direct Use of the Gradient for Investigating Molecular Energy Surfaces.- 1. Gradient Method Versus Pointwise Calculations.- 2. Calculation of the Energy Gradient from SCF Wave Functions.- 2.1. Structure of the Wave Function.- 2.2. First Derivative of the SCF Energy.- 2.3. Definition of the Basis Set in a Distorted Molecule.- 2.4. Hellmann-Feynman Forces and Their Limitations.- 2.5. Computational Aspects.- 2.6. Transformation of Cartesian Forces and Force Constants to Internal Coordinates.- 3. Applications.- 3.1. Molecular Geometries and Reaction Paths.- 3.2. Force Constants.- 4. Analytical Calculation of Higher Energy Derivatives.- References.- 5. Transition Metal Compounds.- 1. Introduction.- 2. The Technique of Ab Initio LCAO-MO-SCF Calculations.- 2.1. The Choice of the Basis Set.- 2.2. The Use of Molecular Symmetry.- 3. Bonding in Transition Metal Compounds.- 3.1. Bondingin "Classical" Complexes: CuCl42-.- 3.2. Bonding in Complexes of ?-Acceptor Ligands: Fe(CO)5.- 3.3. Bonding in Some Organometallics.- 4. The Concept of Orbital Energy and the Interpretation of Electronic and Photoelectron Spectra.- 4.1. Photoelectron Spectra.- 4.2. Electronic Spectra.- 5. Electronic Structure and Stereochemistry of Dioxygen Adducts of Cobalt-Schiff-Base Complexes.- References.- 6. Strained Organic Molecules.- 1. Introduction.- 2. The Nature of Strained Organic Molecules.- 2.1. Definition of Strain.- 2.2. Challenges to Theory.- 3. Theoretical Methods for Strained Organic Systems.- 3.1. Empirical and Semiempirical Methods.- 3.2. Ab Initio Methods and Basis Sets.- 3.3. Localized Molecular Orbitals.- 3.4. Reliability of Ab Initio Methods.- 4. Discussion of Ab Initio Results.- 4.1. Distorted Methane as a Model for Strained Hydrocarbons.- 4.2. Cyclopropane and Cyclobutane.- 4.3. Fused 3- and 4-Membered Ring Systems and the Nature of Bonding between Bridgehead Carbon Atoms.- 4.4. Propellanes.- 4.5. Strained Conjugated Organic Molecules.- 5. Summary.- References.- 7. Carbonium Ions: Structural and Energetic Investigations.- 1. Introduction.- 2. CH+.- 3. CH3+.- 4. CH5+.- 5. C2H+.- 6. C2H3+.- 7. C2H5+.- 8. C2H7+.- 9. C3H+.- 10. C3H3+.- 11. C3H5+.- 12. C3H7+.- 13. C4H5+.- 14. C4H7+.- 15. C4H9+.- 16. C5H5+.- 17. C6H7+.- 18. C7H7+.- 19. C8H9+.- 20. Conclusion.- References.- 8. Molecular Anions.- 1. Introduction.- 2. Background.- 2.1. Calculations of Electron Affinities.- 2.2. A Less Ambitious Target.- 3. Structural Studies.- 3.1. Experimental Comparison.- 3.2. The Methyl Anion.- 3.3. Conformational Studies.- 4. Heats of Reaction.- 4.1. Proton Affinities.- 4.2. Relative Acidities.- 4.3. Anion Hydration.- 5. Mechanistic Studies.- 5.1. Electrocyclic Transformation of Cyclopropyl to the Allyl Anion.- 5.2. Reaction of the Hydride Ion with Small Molecules.- 5.3. The SN2 Reaction.- 6. Conclusions.- References.- 9. Electron Spectroscopy.- 1. Introduction.- 2. Studies of Valence Electrons.- 2.1. Self-Consistent Field Molecular Orbital Methods.- 2.2. Methods Including Electron Correlation.- 3. Studies of Core Electrons.- 3.1. Use of Orbital Energies.- 3.2. Beyond Koopmans' Theorem: More Accurate Theoretical Models.- 4. Summary and Prospectus for the Future.- References.- 10. Molecular Fine Structure.- 1. Introduction.- 2. Theory.- 2.1. Breit-PauliHamiltonian.- 2.2. The ZFS Parameters D and E.- 2.3. Magnitude of Fine-Structure Contributions.- 3. Computational Aspects.- 3.1. Matrix Element Reduction.- 3.2. Integral Evaluation.- 4. Numerical Studies of Fine Structure.- 4.1. Diatomic Molecules.- 4.2. Polyatomic Molecules.- 5. Phenomena Related to Fine Structure.- 5.1. Phosphorescence.- 5.2. Molecular Predissociation.- 6. Conclusions.- Appendix. Vibration-Rotation Corrections to the ZFS Parameters.- References.- Author Index.