Courtesy of John Tully

Last week, chemistry professor John Tully ’64 was named the eighth person to ever win the Ahmed Zewail Prize in Molecular Sciences.

The award –– given by scientific publishing company Elsevier and the editors of the scientific journal Chemical Physics Letters –– is given on a biennial basis to a scientist who “has made significant and creative contributions” to the field of molecular science. The prize recognizes Tully’s achievements in his “surface hopping” technique to understand the motion of molecules in excited states. Tully will receive a monetary prize, a gold medal and a certificate at the Ahmed Zewail Prize Award Symposium in 2021, where he will also deliver a lecture on his work.

“It was a total surprise –– I had no idea that I had been nominated,” Tully said. “There are occasions when somebody makes a breakthrough on his or her own, but more often it’s a team effort. In my case I have to thank my graduate students and collaborators and all. You don’t do these things by yourself.”

Tully’s research focuses on understanding how atoms and molecules move. He said that previous approximations about molecular movement assumed that electrons follow nuclei instantaneously, but that this is not always the case. 

He explained that sometimes the electrons may change their state and “surface hop” from one state to another. His work introduced a model that incorporates this unexpected electron movement.

“What I did was develop ways that you could extend the methods that people had already developed to understand how nuclei move during chemical events to these cases where … you have to take account of the fact that the electrons may change their state, and therefore change the direction of the chemical reaction,” he said.

Tully added that he had been developing his “surface hopping” method since he was a postdoctoral student at Yale in the 1970s. 

Chemistry professor Sharon Hammes-Schiffer said that while there have been various minor contributions and improvements to the method since then, scientists generally return to Tully’s method because of its breadth and accuracy.

“There are lots of situations where you need to take account of the fact that the electrons don’t always follow the nuclei,” Tully said. “For example, any kind of photo-chemistry like photosynthesis and solar energy, or how batteries work or how factories make electronic devices by shining lasers and steering chemical reactions the way they want.”

Rob van Daalan is the publisher of Elsevier’s journal on physical chemistry. He said Tully’s work has been “fundamental” to the advances in catalysis and materials science. 

Hammes-Schiffer added that Tully’s method has “sweeping implications” in the fields of chemistry and biology.

“He is highly respected in the community for having a lot of integrity and for being an excellent human being, as well as a great scientist,” Hammes-Schiffer said. “He’s both brilliant and also a very thoughtful and kind person.”

Tully won the 2020 National Academy of Sciences Award in Chemical Sciences in April. 

Julia Brown |

Julia Brown served as University Editor on the Managing Board of 2023. Previously, she covered the University's graduate and professional schools as a staff reporter. She graduated cum laude from Yale University with a B.A. in Economics & Mathematics.