This book is based mostly on the reports presented at the XVth International lahn-Teller Symposium on Vibronic Interactions in Crystals and Molecules and NATO Advanced Research Workshop Colossal Magnetoresistance and Vibronic Interactions that took place at Boston on August 16-22 of the year 2000. This is the first time the Symposium took place in the USA where recently the giant splash of the attention to the 1 ahn-Teller effect occurred. This tremendous interest to the field all over the world is reflected not only in the numerous publications in many American and European 10urnals, but of the leading scientists from additionally in the Symposium's participation the well known Universities, National Laboratories and industrial companies, which was the largest in the history of the Symposium. The renaissance of the 1ahn-Teller physics is closely related to the three fundamental discoveries in science. The most significant among them is the discovery of high-Tc superconductivity by K. -A. Muller and G. Bednorz, for whom the "1ahn-Teller idea" was the motivation in their search. The result of this search is well known - a wide spectrum of the 1ahn-Teller ion based materials with Tc between 24K and 135K were found. The second discovery is the existence of a new polymorph of carbon - the C60. The microscopic analysis of all physical, chemical and biological properties of the buckyballs is based on 1ahn-Teller type of interactions. The third is colossal magnetoresistance.

This book by Kaplan and Vekhter brings together the molecular world of the chemist with the condensed matter world of the physicist. Prior to the collapse of the Soviet Union, chemists in the West devoted lit to relationships between molecular electronic structure and tle attention solid-state vibronic phenomena. Treating quantum mechanical problems wherein the adiabatic Born-Oppenheimer approximation fails was done by "brute force. " With bigger and better computers available in the West, molecular orbital calculations were done on observed and conceived static structures with little concern for any cooperativity of vibrational behavior that might connect these states. 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. It was easier to calculate the electronic structure observed with several possible distortions than to focus on ways to couple electronic and vibrational behavior. In the former Soviet Union, computational power was not as acces sible as in the West. Much greater attention, therefore, was devoted to conserving computational time by considering fundamental ways to han dle the vibrational connectivity between degenerate or nearly degenerate electronic states.

This book by Kaplan and Vekhter brings together the molecular world of the chemist with the condensed matter world of the physicist. Prior to the collapse of the Soviet Union, chemists in the West devoted lit to relationships between molecular electronic structure and tle attention solid-state vibronic phenomena. Treating quantum mechanical problems wherein the adiabatic Born-Oppenheimer approximation fails was done by "brute force. " With bigger and better computers available in the West, molecular orbital calculations were done on observed and conceived static structures with little concern for any cooperativity of vibrational behavior that might connect these states. 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. It was easier to calculate the electronic structure observed with several possible distortions than to focus on ways to couple electronic and vibrational behavior. In the former Soviet Union, computational power was not as acces sible as in the West. Much greater attention, therefore, was devoted to conserving computational time by considering fundamental ways to han dle the vibrational connectivity between degenerate or nearly degenerate electronic states.

This book is based mostly on the reports presented at the XVth International lahn-Teller Symposium on Vibronic Interactions in Crystals and Molecules and NATO Advanced Research Workshop Colossal Magnetoresistance and Vibronic Interactions that took place at Boston on August 16-22 of the year 2000. This is the first time the Symposium took place in the USA where recently the giant splash of the attention to the 1 ahn-Teller effect occurred. This tremendous interest to the field all over the world is reflected not only in the numerous publications in many American and European 10urnals, but of the leading scientists from additionally in the Symposium's participation the well known Universities, National Laboratories and industrial companies, which was the largest in the history of the Symposium. The renaissance of the 1ahn-Teller physics is closely related to the three fundamental discoveries in science. The most significant among them is the discovery of high-Tc superconductivity by K. -A. Muller and G. Bednorz, for whom the "1ahn-Teller idea" was the motivation in their search. The result of this search is well known - a wide spectrum of the 1ahn-Teller ion based materials with Tc between 24K and 135K were found. The second discovery is the existence of a new polymorph of carbon - the C60. The microscopic analysis of all physical, chemical and biological properties of the buckyballs is based on 1ahn-Teller type of interactions. The third is colossal magnetoresistance.