Intermolecular Forces—An Example of Fruitful Cooperation of Theory and Experiment

New experimental techniques and extensive ab initio calculations have rendered it possible to gain a detailed knowledge of aggregates of atoms, small ions and/or small molecules in the vapor phase which are held together by intermolecular forces. Theory and experiment are often complementary regarding reliable predictions. The results obtained for complexes of three or more constituents are still fragmentary; nevertheless, they can be used to explain some properties of the condensed phase.