1 Introduction 1
1.1 What Is a Molecule？ 1
1.2 Goals and Methods 3
1.3 Historical Remarks 4
1.4 The Significance of Molecular Physics and Quantum Chemistry for Other Fields 7
2 Mechanical Properties of Molecules，Their Size and Mass 9
2.1 Molecular Sizes 9
2.2 The Shapes of Molecules 17
2.3 Molecular Masses 19
2.4 Specific Heat and Kinetic Energy 21
Problems 23
3 Molecules in Electric and Magnetic Fields 27
3.1 Dielectric Properties 27
3.2 Nonpolar Molecules 29
3.3 Polar Molecules 33
3.4 Index of Refraction，Dispersion 36
3.5 The Anisotropy of the Polarisability 39
3.6 Molecules in Magnetic Fields，Basic Concepts and Definitions 40
3.7 Diamagnetic Molecules 42
3.8 Paramagnetic Molecules 44
Problems 46
4 Introduction to the Theory of Chemical Bonding 51
4.1 A Brief Review of Quantum Mechanics 51
4.2 Heteropolar and Homopolar Bonding 56
4.3 The Hydrogen Molecule-Ion，H+ 2 58
4.4 The Hydrogen Molecule，H2 65
4.4.1 The Variational Principle 65
4.4.2 The Heitler-London Method 66
4.4.3 Covalent-Ionic Resonance 75
4.4.4 The Hund-Mullikan-Bloch Theory of Bonding in Hydrogen 76
4.4.5 Comparison of the Wavefunctions 77
4.5 Hybridisation 78
Problems 83
5 Symmetries and Symmetry Operations：A First Overview 89
5.1 Fundamental Concepts 89
5.2 Application to Benzene：the π-Electron Wavefunctions by the Hückel Method 93
5.3 The Hückel Method Revisited，The Energy of the π-Electrons 97
5.4 Slater Determinants 101
5.5 The Ethene Wavefunctions．Parity 102
5.6 Summary 103
Problems 104
6 Symmetries and Symmetry Operations．A Systematic Approach 107
6.1 Fundamentals 107
6.2 Molecular Point Groups 112
6.3 The Effect of Symmetry Operations on Wavefunctions 116
6.4 Similarity Transformations and Reduction of Matrices 119
6.5 Fundamentals of the Theory of Group Representations 122
6.5.1 The Concept of the Class 122
6.5.2 The Character of a Representation 123
6.5.3 The Notation for Irreducible Representations 127
6.5.4 The Reduction of a Representation 128
6.6 Summary 131
6.7 An Example：The H2O Molecule 132
Problems 142
7 The Multi-Electron Problem in Molecular Physics and Quantum Chemistry 147
7.1 Overview and Formulation of the Problem 147
7.1.1 The Hamiltonian and the Schr？dinger Equation 147
7.1.2 Slater Determinants and Energy Expectation Values 148
7.2 The Hartree-Fock Equation．The Self-Consistent Field（SCF）Method 151
7.3 The Hartree-Fock Method for a Closed Shell 151
7.4 The Unrestricted SCF Method for Open Shells 153
7.5 The Restricted SCF Method for Open Shells 154
7.6 Correlation Energies 156
7.7 Koopman's Theorem 156
7.8 Configuration Interactions 157
7.9 The Second Quantisation 159
7.10 Résumé of the Results of Chapters 4-7 161
Problems 162
8 Overview of Molecular Spectroscopy Techniques 165
8.1 Spectral Regions 165
8.2 An Overview of Optical Spectroscopy Methods 166
8.3 Other Experimental Methods 169
Problems 170
9 Rotational Spectroscopy 171
9.1 Microwave Spectroscopy 171
9.2 Diatomic Molecules 172
9.2.1 The Spectrum of the Rigid Rotor （Dumbbell Model） 172
9.2.2 Intensities 178
9.2.3 The Non-rigid Rotor 179
9.3 Isotope Effects 182
9.4 The Stark Effect 184
9.5 Polyatomic Molecules 186
9.6 Some Applications of Rotational Spectroscopy 190
Problems 190
10 Vibrational Spectroscopy 193
10.1 Infrared Spectroscopy 193
10.2 Diatomic Molecules：Harmonic Approximation 194
10.3 Diatomic Molecules．The Anharmonic Oscillator 198
10.4 Rotational-Vibrational Spectra of Diatomic Molecules．The Rotating Oscillator and the Rotational Structure of the Bands 205
10.5 The Vibrational Spectra of Polyatomic Molecules 212
10.6 Applications of Vibrational Spectroscopy 218
10.7 Infrared Lasers 219
10.8 Microwave Masers 220
Problems 222
11 The Quantum-Mechanical Treatment of Rotational and Vibrational Spectra 225
11.1 The Diatomic Molecule 225
11.1.1 The Born-Oppenheimer Approximation 225
11.1.2 Justification of the Approximations 232
11.2 The Rotation of Tri-and Polyatomic Molecules 234
11.2.1 The Expression for the Rotational Energy 234
11.2.2 The Symmetric Top 237
11.2.3 The Asymmetric Top 238
11.3 The Vibrations of Tri-and Polyatomic Molecules 242
11.4 Symmetry and Normal Coordinates 249
11.5 Summary 255
Problems 256
12 Raman Spectra 257
12.1 The Raman Effect 257
12.2 Vibrational Raman Spectra 258
12.3 Rotational Raman Spectra 262
12.4 The Influence of Nuclear Spins on the Rotational Structure 267
Problems 271
13 Electronic States 275
13.1 The Structure of Band Spectra 275
13.2 Types of Bonding 276
13.3 Electronic States of Diatomie Molecules 276
13.4 Many-Electron States and Total Electronic States of Diatomic Molecules 284
13.5 An Example：the Electronic States of H2 293
Problems 294
14 The Electronic Spectra of Molecules 295
14.1 Vibrational Structure of the Band Systems of Small Molecules；The Franck-Condon Principle 295
14.2 The Rotational Structure of Electronic Band Spectra in Small Molecules；Overview and Selection Rules 303
14.3 The Rotational Structure of the Band Spectra of Small Molecules；Fortrat Diagrams 305
14.4 Dissociation and Predissociation 310
14.5 Applications of Band Spectra of Smaller Molecules 314
14.6 The Electronic Spectra of Larger Molecules 316
Problems 324
15 Further Remarks on the Techniques of Molecular Spectroscopy 327
15.1 The Absorption of Light 327
15.2 Radiationless Processes 330
15.3 The Emission of Light 331
15.4 Cold Molecules 333
15.5 Dye Lasers 338
15.6 High-Resolution Two-Photon Spectroscopy 339
15.7 Ultrashort Pulse Spectroscopy 342
15.8 Photoelectron Spectroscopy 343
15.9 High-Resolution Photoelectron Spectroscopy 348
Problems 349
16 The Interaction of Molecules with Light：Quantum-Mechanical Thatment 353
16.1 An Overview 353
16.2 Time-Dependent Perturbation Theory 354
16.3 Spontaneous and Stimulated Emission and the Absorption of Light by Molecules 360
16.3.1 The Form of the Hamiltonian 360
16.3.2 Wavefunctions of the Initial and Final States 363
16.3.3 The General Form of the Matrix Elements 363
16.3.4 Transition Probabilities and the Einstein Coefficients 366
16.3.5 The Calculation of the Absorption Coefficient 373
16.3.6 Transition Moments，Oscillator Strengths，and Spatial Averaging 374
16.4 The Franck-Condon Principle 378
16.5 Selection Rules 381
16.6 Summary 385
17 Theoretical Tratment of the Raman Effect and the Elements of Nonlinear Optics 387
17.1 Time-Dependent Perturbation Theory in Higher Orders 387
17.2 Theoretical Description of the Raman Effect 390
17.3 Two-Photon Absorption 400
18 Nuclear Magnetic Resonance 403
18.1 Fundamentals of Nuclear Resonance 403
18.1.1 Nuclear Spins in a Magnetic Field 403
18.1.2 Detection of Nuclear Resonance 406
18.2 Proton Resonance in Molecules 407
18.2.1 The Chemical Shift 407
18.2.2 Fine Structure and the Direct Nuclear Spin-Spin Coupling 412
18.2.3 Fine Structure and the Indirect Spin-Spin Coupling Between Two Nuclei 413
18.2.4 The Indirect Spin-Spin Interaction Among Several Nuclei 415
18.3 Dynamic Processes and Relaxation Times 418
18.4 Nuclear Resonance with Other Nuclei 422
18.5 Two-Dimensional Nuclear Resonance 423
18.5.1 The Basic Concepts 423
18.5.2 The Quantum-mechanical Theory of COSY 426
18.5.3 The Investigation of Dynamic Processes Using 2-Dimensional Exchange Spectroscopy，in particular NOESY 431
18.6 Applications of Nuclear Magnetic Resonance 435
Problems 435
19 Electron Spin Resonance 441
19.1 Fundamentals 441
19.2 The g-Factor 443
19.3 Hyperfine Structure 443
19.4 Fine Structure 451
19.5 Calculation of the Fine Structure Tensor and the Spin Wavefunctions of Triplet States 453
19.6 Double Resonance Methods：ENDOR 461
19.7 Optically Detected Magnetic Resonance（ODMR） 463
19.8 Applications of ESR 468
Problems 469
20 Macromolecules，Biomolecules，and Supermolecules 473
20.1 Their Significance for Physics，Chemistry，and Biology 473
20.2 Polymers 475
20.3 Molecular Recognition，Molecular Inclusion 479
20.4 Energy Transfer，Sensitisation 482
20.5 Molecules for Photoreactions in Biology 486
20.6 Molecules as the Basic Units of Life 490
20.7 Molecular Functional Units 494
Problems 500
21 Experiments on and with Single Molecules 503
21.1 Introduction：Why？ 503
21.2 The Imaging of Single Molecules with X-ray and Electron Beam Methods 504
21.3 Scanning Tunnel and Atomic Force Microscopes 505
21.4 Optical Spectroscopy of Single Molecules 508
21.4.1 Overview 508
21.4.2 Experimental Methods 510
21.4.3 Single-Molecule Spectroscopy with Relatively Limited Resolution：Spatial Selection 511
21.4.4 Measurements with a High Spectral Resolution at Low Temperatures：Spectral Selection 512
21.4.5 Some Experimental Results 516
21.5 The Electrical Conductivity ofMolecules 520
21.5.1 Molecular Wires 520
21.5.2 Experimental Results 523
22 Molecular Electronics and Other Applications 527
22.1 What Is It？ 527
22.2 Molecules as Switching Elements 528
22.3 Molecular Electrical Conductors 533
22.4 Molecular Wires 538
22.5 Molecules as Energy Conductors 542
22.6 Molecular Electronic Functional Units 548
22.7 Nanotubes 552
22.8 Molecular Storage Elements，Hole-Burning 554
22.9 Electroluminescence and Light-Emitting Diodes 557
22.10 The Future：Intelligent Molecular Materials 558
Problems 558
Appendix 561
A.1 The Calculation of Expectation Values Using Wavefunctions Represented by Determinants 561
A.1.1 Calculation of Determinants 561
A.1.2 Calculation of Expectation Values 562
A.2 Calculation of the Density of Radiation 566
Bibliography 569
Subject Index 577