While it had long been understood in the West that situations do occur in which different static structures are found for molecules that have identical or nearly identical electronic structures, little attention had been paid to understanding the vibrational states that could connect such structures.
1. The Jahn—Teller Effect.- 1.1. The Jahn—Teller Theorem.- 1.2. Electron-Vibration Coupling in the Case of Electronic Degeneracy.- 1.3. Typical Jahn—Teller Situations.- 1.4. Interaction with Rotations and Quadratic Vibronic Coupling.- 1.5. Situations Similar to the Jahn—Teller Effect.- 1.6. Manifestation of the Jahn—Teller Effect.- 1.7. Examples of Jahn—Teller Systems.- References.- 2. Interaction of Jahn—Teller Centers.- 2.1. Direct Exchange in Orbital Degeneracy.- 2.2. Superexchange in Orbital Degeneracy.- 2.3. Indirect Exchange through Conduction Electrons.- 2.4. Multipole Interactions.- 2.5. Interaction of Ions through the Exchange of Virtual Phonons.- 2.6. The Cooperative Jahn—Teller Effect.- 2.7. Types of Jahn—Teller Orderings.- References.- 3. The Elastic Properties of Crystals with Jahn—Teller Structural Phase Transitions.- 3.1. Tetragonal ? Orthorhombic Phase Transitions with Twofold-Degenerate States.- 3.2. Cubic ? Tetragonal Structural Phase Transitions in Crystals with a Threefold-Degenerate Ionic Ground State.- 3.3. Structural Phase Transitions Induced by the Cooperative Pseudo Jahn—Teller Effect.- 3.4. Characteristics of Structural Phase Transitions in Singlet-Doublet-Singlet Systems.- 3.5. The Cooperative Jahn—Teller Effect in Dynamic Electron-Phonon Coupling.- 3.6. Anomalies of “Nonsoft” Elastic Constants in Jahn—Teller Structural Phase Transitions.- References.- 4. Mutual Influence of Distortive, Magnetic, and Electric Dipole Orderings in Jahn—Teller Elastics.- 4.1. Mutual Quenching of Structural and Magnetic Orderings.- 4.2. Mutual Enhancement of Structural and Magnetic Orderings.- 4.3. Magnetic Anisotropy and Noncollinearity of Magnetic Structures.- 4.4. High Spin-Low Spin Phase Transitions.- 4.5. Domain Walls inthe Competition of Structural and Magnetic Orderings.- 4.6. Interrelationship between Acoustical and Dielectric Anomalies in Ferrodistortive Antiferroelectrics.- 4.7. Antiferrodistortive Ferroelectric Transitions.- 4.8. Interrelationship between Distortive and Electric Dipole Structures in Noncentrosymmetric Crystals.- 4.9. Anomalies of the “Transverse” Dielectric Susceptibilities.- 4.10. Coexistence of Spontaneous Strains of Different Symmetries in Mixed Crystals.- References.- 5. Jahn—Teller Crystals in External Fields: Phase Diagrams and Properties.- 5.1. Phenomenological Description of Striction in Jahn—Teller Crystals.- 5.2. Dynamic Magnetostriction of Systems with Mutual Suppression of Magnetic and Distortive Interactions.- 5.3. Dynamic Magnetostriction of Systems with Mutual Enhancement of Magnetic and Distortive Interactions.- 5.4. Anomalous Electrostriction and Magnetoelectric Effects.- 5.5. Metamagnetoelasticity of Antiferroelastics.- 5.6. Structural Transitions Stimulated by a Magnetic Field.- 5.7. Magnetodistortive Phase in Jahn—Teller Antiferromagnetics and Its Properties.- 5.8. Anomalous Magnetic Nonlinearity of Elastics.- 5.9. Electric Field-Induced Ferroelastic-Antiferroelastic Phase Transition.- 5.10. Reorientational Structural Phase Transitions in Jahn—Teller Crystals.- References.- 6. The Dynamics of Jahn—Teller Crystals.- 6.1. Electron-Phonon Modes and Sound Absorption.- 6.2. Frequency Dependence of the Response Functions.- 6.3. Mixed Electron-Phonon Modes in Crystals with Several Jahn—Teller Ions in the Unit Cell.- 6.4. Hyperfine Interaction and Nuclear Sound Absorption.- 6.5. Parametric Sound Generation.- 6.6. The Central-Peak Problem.- 6.7. Transport Phenomena in Jahn—Teller Crystals; Thermal Conductivity.- References.
