The Jahn-Teller Effect

TheJahn Teller(JT)effectcontinuesto bea paradigmforstructuralinstabilitiesand dynamicalprocessesinmoleculesandin the condensedphase.While thebasic th- rem, rst published in 1937, had to await experimentalveri cation for 15 years, the intervening years saw rapid development, initially in the theoretical arena, followed increasingly by experimental work on molecules and crystals. The International Jahn Teller Symposiumwas established in the mid-1970s, to foster the exchangeof ideas between researchers in the eld. Among the many important developments in the eld, we mention cooperative phenomena in crystals, the general importance of pseudo-Jahn Teller (PJT) couplings for symmetry-lowering phenomena in mol- ular systems, nonadiabatic processes at conical intersections of potential energy surfaces and extensions of the basic theory in relation to the discovery of fullerenes and other icosahedral systems. It is the objectiveof this volume to providethe interested reader with a collection of tutorial reviews by leading researchers in the eld. These reviews provide a c- prehensive overview of the current status of the eld, including important recent developments.This volume is targeted at both the non-expertscientist as well as the expert who wants to expand his/her knowledge in allied areas. It is intended to be a complement to the existing excellent textbooks in the eld. Guided by the idea of tutorial reviews, we provide here short introductoryremarks to the various sections, astheyappearin thetable ofcontents.These arefollowedbya briefcharacterization of the individual papers to make their basic contents, as well as their interrelation, more transparent."