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John C. Tully

Sterling Professor of Chemistry, Professor of Physics and Applied Physics, Physical & Theoretical Chemistry
E-mail: john.tully@yale.edu
Web site: http://www.chem.yale.edu/~tully

Biographical Sketch

B.S. Yale University, 1964
Ph.D. University of Chicago, 1968
National Science Foundation Postdoctoral Fellow, University of Colorado and Yale University, 1968-1970
Joined Yale faculty in 1996
Fellow, American Physical Society, 1978
AT&T Bell Laboratories Distinguished Technical Staff Award, 1982
AT&T Bell Laboratories Affirmative Action Award, 1992
Fellow, American Association for the Advancement of Science, 1992
American Chemical Society Peter Debye Award in Physical Chemistry, 1995
Fellow, American Academy of Arts and Sciences, 1997
Member, U. S. National Academy of Sciences, 1997
Member, Connecticut Academy of Science and Engineering, 1998
American Chemical Society Madison Marshall Award, 1999
Member, International Academy of Quantum Molecular Sciences, 2000
Special Issue of the Journal of Physical Chemistry: “John C. Tully Festschrift,” 2002
American Chemical Society Award in Theoretical Chemistry, 2004

Research Description

The objective of our research is to achieve a theoretical understanding at the molecular level of dynamical processes such as energy transfer and chemical reaction at surfaces, in condensed-phases, and in biological environments. This requires both the development of novel theoretical and computational tools, as well as the application of these tools to challenging chemical problems, with direct coupling to experiments wherever possible. Two recent studies are described below.

The first is a theoretical and computational study of vibrational energy transfer within an adsorbed layer of CO molecules on a NaCl crystal surface, carried out by graduate student Steve Corcelli. Adsorbate vibrational excitations on insulator surfaces can be very long-lived if the molecular vibrational frequency is much greater than the Debye frequency of the solid. This allows time for vibrational excitations to hop resonantly among neighbors a great many times before de-excitation. Sometimes this will result in two adjacent adsorbate molecules both excited to v=1. As a result of anharmonicity, a state with one molecule in v=2 and one in v=0 has a slightly lower energy than both molecules in v=1. Similarly, 3 quanta of vibration shared by two neighboring adsorbate molecules produce a lower total energy if all 3 quanta reside on one of the molecules. This produces a driving force for “pooling” of energy into highly excited molecules. This effect has been demonstrated experimentally [H.-C. Chang and G. E. Ewing, Phys. Rev. Lett. 65, 2125 (1990)] who observed population of vibrational levels as high as v=15 for CO on NaCl. Steve has developed a perturbation theory approach to calculate all of the operative rate processes; vibrational relaxation, resonant hopping, pooling, and radiation. He has used these rates in a kinetic Monte Carlo simulation of the energy pooling process, enabling him to compute the number of quanta of vibration in each CO molecule, as illustrated in the figure. His results are in qualitative agreement with experiment, and reveal interesting phenomena such as self-trapping and Ostwald ripening. In addition, he predicts an enormous ¹²C/¹³C isotope effect.

A second example is a study of hydrophobic interactions of solutes in water, carried out by graduate student Laura LaBerge. Understanding the behavior of biomolecules requires knowledge of their interaction with water, as such interactions are believed to play a driving role in most intracellular processes. In particular, the energetics of removing water molecules from between hydrophobic surfaces is crucial to understanding such phenomena as protein folding and docking. Laura has carried out Monte Carlo simulations of water molecules between semi-infinite hydrophobic plates. She observes evacuation of water between the plates when the plate separation is reduced to 5 angstroms, but not for 9 or 16 angstrom separations. The figure shows the 5 angstrom case, with the channel initially filled with water (left), then partially evacuated (middle) and finally the fully evacuated equilibrium state (right). This contrasts with simulations of water between infinite hydrophobic plates, which do not reproduce such drying. The semi-infinite plate simulations show a significant ‘edge stabilization’; water molecules near the edges of the slabs have a lower average potential energy and are more completely hydrogen bonded than molecules near the center of the slabs. This stabilization extends well beyond the first solvation shell, possibly beyond fourth neighbor interactions, and strongly effects the nature of the drying transition.

Selected References

• “Nonadiabatic dynamics via the classical limit Schrodinger equation,” J. C. Burant and J. C. Tully, J. Chem. Phys. 112, 6097 (2000).
• “Chemical Dynamics at Metal Surfaces,” J. C. Tully, Ann. Revs. Phys. Chem. 51, 153 (2000).
• “Puddle-jumping: a flexible sampling algorithm for rare event systems,” J. A. Rahman and J. C. Tully, Chem. Phys. 285, 277 (2002).
• “Vibrational Energy Pooling in CO on NaCl(100): Simulation and Isotope Effects,” S. A. Corcelli and J. C. Tully, J. Phys. Chem. 106, 10849 (2002).
• “Efficient thermal rate constant calculation for rare event systems,” S. A. Corcelli, J. A. Rahman and J. C. Tully, J. Chem. Phys. 118, 1085 (2003).

Last modified: February 15, 2006 (rjc)