The present symposium brings together research in a number of fields: the quantum-chemical calculation of molecular potential-energy surfaces, rotational–vibrational spectroscopy, methods of calculating rotational–vibrational energy levels, unimolecular reactions and intramolecular dynamics. Several aspects of the work are discussed including some recent developments on rates and products' quantum state distributions for unimolecular dissociations having highly flexible transition states. The usefulness of having improved potential-energy surfaces, particularly the bonding and hindered rotational potentials in the dissociations, is noted. In various other studies in this symposium a better knowledge of the surfaces would be particularly helpful. New results on a semiclassical quantization method are also described.