In 2002, he moved to the University of Oxford, where he was head of the Division of Mathematical and Physical Sciences and professorial fellow of St John's College.

[6] The citation for his knighthood stated: "Professor Clary has made an outstanding contribution to enhancing the international reputation of UK science and higher education.

"[7] The citation for his election as a Fellow of the Royal Society states: "Professor Clary is distinguished for his use of quantum collision theory as a practical tool for explaining a wide variety of experimental results in chemical reaction dynamics.

His general theories and computational methods enable reliable predictions to be made on the reactions, energy transfer and dissociation of polyatomic molecules in selected quantum states.

His work also has important applications in understanding interstellar, combustion and atmospheric chemistry, as the extreme temperatures of these environments can be hard to reproduce in the laboratory, but are readily treated with these theoretical methods.

[9] He is an authority on Erwin Schrödinger, the discoverer of the form of quantum theory known as wave mechanics and Fellow of Magdalen College, Oxford.