A unique Jahn-Teller mechanism of all the symmetry breakings in molecular systems and condensed matter

An attempt is made to present all the symmetry breakings (SB) in molecular systems and condensed matter from a unique point of view as controlled by the electronic structure, degeneracy and pseudodegeneracy, via the Jahn-Teller (JT) vibronic coupling effects [JT, Renner-Teller (RT), and pseudo Jahn-Teller (PJT) effects]. For chemically bonded systems in high-symmetry configurations and transition states of chemical reactions, as proved earlier, the JT effects are the only possible source of spontaneous distortion, which is the necessary condition of SB. It is shown that the JT (and related RT and PJT) effects are directly applicable to chemically nonbonded systems: formation of molecules from atoms (chemical bonding), as well as intermolecular interaction, can be regarded as particular cases of JT effects. This closes the gap in considering all the SB in molecular systems as triggered by JT effects. It stimulated also a general (extended and more rigorous) formulation of the JT theorem to include all the vibronic coupling effects and recent achievements in the JT effect theory. Added to the JT origin of structural phase transitions and liquid-solid transition, considered earlier, and gas-liquid transition shown to be in principle of the same JT origin, the results above lead us to a general conclusion that spontaneous SB in molecular systems and condensed matter are always associated with degeneracy or pseudodegeneracy and realized via JT vibronic coupling effects. Together with the concept of SB in particle physics as associated with degeneracy, we can speculate about a general picture of consecutive transformations of matter via similar in nature degeneracy-based SB, beginning with the Big Bang. © 2003 Elsevier Inc. All rights reserved.