This book is the result of the joint efforts of a group of lecturers who came together in Istanbul in the summer of 1964 to lecture on Modern Quantum Chemistry. The lectures follow a definite sequence and attempt to present a detailed, up-to-date, and coherent picture of modern quantum chemistry to graduate students and researchers. The book is in three parts, Part I on orbitals, Part II on interactions and effects of electron correlation, and Part III on action of light and organic crystals. The parts are connected, though each is quite self-contained. The book should be useful for advanced quantum chemistry courses, as well as a reference. Parts I, II, and III may be used individually or in combination. Each lecture, by and large, starts with an introduction, before proceeding to current developments and problems. Many lectures contain new work and approaches not published before. The over-all theoretical picture that emerges applies to electronic properties, stabilities, and spectra of saturated and unsaturated molecules, sigma and pi systems, and also to intermediate species, radicals, and triplet states. |
Modern Quantum Chemistry - Istanbul Lectures 1965 CONTENTS List of Contributors to Part I ................................ v Preface ....................................................... vii Condensed Table of Contents of Parts I - III .................. xiii Introduction, Parts I - III, O. Sinanoğlu ..................... 1 Section I. A. Saturated Compounds 1. Present Status of the Theory of Electronic Structure of Molecules ROBERT G. PARR 1. The Problem ............................................... 5 2. One- and Two-Electron Cases ............................... 6 3. Preliminaries for Many-Electron Cases ..................... 9 4. Many-Electron Cases ....................................... 10 3. Implementation ............................................ 13 6. Conclusion ................................................ 14 2. Chemical Predictions by MO Theory : The Rare Gas Halides JOSHUA J0RTNER and STUART A. RICE 1. Introduction .............................................. 15 2. The Electron-Correlation Model ............................ 16 3. The Molecular Orbital Model ............................... 18 4. The Valence Bond Model .................................... 25 5. Interpretation of Physical Properties ..................... 28 6. Excited Electron States ................................... 33 7. Discussion of the Theoretical Models ...................... 43 References ................................................ 45 3. Sigma Molecular Orbital Theory and Chemical Reactivity KENICHI FUKUI 1. Introduction .............................................. 49 2. Sigma Molecular Orbital ................................... 49 3. Chemical Reactivity Theory ................................ 59 4. Electron Delocalization at the Transition State ........... 63 5. Simple Interpretation of Reactivity of Saturated Compounds 70 6. Conclusion ................................................ 81 References ................................................ 63 4. Localized Self-Consistent Field Orbitals in Atoms ond Molecules KLAUS RUEDENBERG 1. Introduction .............................................. 85 2. Arbitrariness of Hartree-Fock Orbitals .................... 86 3. Fixation of Hartree-Fock Orbitals ......................... 88 4. Canonical SCF Orbitals .................................... 89 5. Externally Localized SCF Orbitals ......................... 89 6. Intrinsically Localized SCF Orbitals ...................... 90 7. Choice of Separation Function f(r_{12 }) ...................... 92 8. Construction of Localized Orbitals from an Arbitrary Set of SCF Orbitals ....................................... 93 9. Localized Orbitals and Molecular Symmetry ................. 93 10. Localized Orbitals in the Absence of Symmetry ............. 95 11. Localized Molecular Orbitals in Delocalized Electronic Systems 98 References ................................................ 99 5. Integral Hellmann-Feynman Theorem, Barriers to lnternal Rotations, and Isoelectronic Processes ROBERT G. PARR 1. Integral Hellmann-Feynman Theorem ......................... 101 2. Barriers to Internal Rotation ............................. 102 3. Isoelectronic Processes ................................... 104 References ................................................ 105 Section I. B. Pi-Electron Systems 1. General Survey of Pi-Electron Methods and Problems ROBERT 0. PARR 1. Pi-Electron Approximation ................................. 107 2. Pi-Electron Methods ....................................... 109 3. Pi-Electron Problems ...................................... 110 References ................................................ 112 2. Three-Dimensional and One-Dimensional Free-Electron Molecular Orbitals RICHARD L. HUMMEL and KLAUS RUEDENBRRG 1. Introduction .............................................. 113 2. General Solution .......................................... 114 3. Determination of Eigenvalues as Functions of Delta ........ 116 4. One-Dimensional Model ..................................... 118 5. Comparison of Energies .................................... 119 6. Comparison of Wavefunctions ............................... 120 7. Conclusion ................................................ 121 Appendix .................................................. 122 References ................................................ 123 3. Self-Consistent Field Theory of Noncloned Shell Systems with Application to Pi-Electron Systems R. LEFEBVRE 1. Introduction ............................................... 125 2. Self-Consistent Field Equations for s Closed Shell System. The Brillouin Theorem .................................. 126 3. Self-Consistent Conditions for a Doublet State with One Nonclosed Shell ........................................ 128 4. Self-Consistent Conditions for a Triplet State with Two Nonclosed Shells ....................................... 131 5. The Lowest Triplet Excitation Energies of Some Even Alternant Hydrocarbons Calculated to Various Degrees of Self-Consistency .................................... 132 Summary .................................................... 134 Referestces ................................................ 134 4. Charge Transfer and Radical lons L. J. OOSTERHOFF 1. Introduction ............................................... 137 2. Formulae ................................................... 139 3. Loosely Bound and Semi-ionic Complexes: Benzene-Iodine and Trimethylamine-Iodine ................. 142 4. Ionic Compounds: Sodium Iodide ............................. 145 5. The Organic Chemist's View of the Problem .................. 148 6. Radical Ions ............................................... 151 7. Photoionization ............................................ 152 References ................................................. 154 5. Some Properties of Pi-lons and Triplets A. T. AMOS 1. Introduction ................................................ 157 2. Restricted Hartree-Fock ..................................... 157 3. Unrestricted Hartree-Fock ................................... 158 4. Energies and Charge Densities ............................... 159 5. The Transformation Properties of the Orbitals ............... 161 6. Spin Properties of Psi(UHF) ................................. 164 7. Zero-Field Splitting in Triplet States ...................... 167 8. Conclusion .................................................. 169 References .................................................. 169 6. Critical Examination of Pi-Electron Theories a. Applicability of the Hückel and Pariser-Parr-Type Methods J. KOUTECKÝ Text ....................................................... 171 References ................................................. 182 b. Orbital Basis of Zero Differential Overlap INGA FISCHER-HJALMARS 1. Introduction ................................................. 185 2. Expansion Method ............................................. 187 3. Applications to the Fock Operator ............................ 189 4. Reformulation of the ZDO Assumption .......................... 192 References ................................................... 193 c. Electron Distribution In Heteromolecules R. DAUDEL 1. Importance of the Notion of Charge ........................... 195 2. Pariser, Parr, and Hückel (or Pauling and Wheland) Approxinsations ........................................ 195 3. The Nature of the Pariser and Parr Approximations ............ 196 4. Effect of the Introduction of OAO's on the pi-Electron Distribution ........................................... 197 5. Comparison between Pariser, Parr. and Pople Method and Hückel Method ..................................... 199 References .................................................. 202 d. Semiempirical Parameters in MO Theory INGA FISCHER-HJALMARS 1. Introduction ................................................. 203 2. One-Center Integrals ......................................... 203 3. Two-Center Integrals ......................................... 210 References ................................................... 213 e. Extended CI Calculations on Benzene J. KOUTECKÝ Text ....................................................... 215 References ................................................. 220 f. The Pi-Electron Approximation and Coulomb Repulsion Parameters 0. SINANOGLU and M. K. ORLOFF 1. The Pi-Electron Approximation ................................ 221 2. Coulomb Repulsions Parameters ................................ 225 References ................................................... 231 AUTHOR INDEX .................................................... 233 SUBJECT INDEX ................................................... 239