This volume is the first of a set of two which contain the invited lectures given at the international seminar of the same title held at the Centre de Mecanique

This volume is the second of a set of two which contain 28 selected from the l. j. O invited lectures given at the internatim;al seminar of the same title held

This volume contains a selection of scientific papers related to the structure and dynamics of non-rigid molecules. This frontline topic was born a few decades