Physical and Theoretical Chemistry
My research group creates and uses new theoretical and computational approaches to study complex systems in materials science, condensed-matter physics, and physical chemistry.
We look for new phenomena that occur when different components are brought together. For example, we examine molecules adsorbing on metal surfaces, in order to understand the effect of surface composition and structure on preferred adsorption sites, dissociation pathways, and vibrational dynamics. We also study how the compositions of oxide solid solutions lead to Angstrom-scale chemical structure, nanometer scale structural disorder, and long-range ferroelectric and piezoelectric properties. These studies find real-world applications in catalysis, corrosion, SONAR, fuel cells and other important technologies. Whenever possible, we model systems analytically, in order to extract general principles and simple pictures from complex systems. We recently derived general expressions for the vibrational lifetimes of molecules on surfaces, revealing the dependence of lifetime on molecular coverage and arrangement. Our recent exploration of quantum stress fields has helped to link chemical and mechanical effects in materials.
We are constantly developing methods for computing new properties, and for making quantum-mechanical calculations more accurate and more efficient. We tailor computational algorithms to maximize performance on modern computing platforms such as Beowulf clusters. Wherever possible, we also model systems analytically, in order to extract general principles and simple pictures from complex systems. This combination of theoretical and computational tools enables us to identify new phenomena in complex systems, like multicenter bonds between methyl radicals and the rhodium surface. ( See figure below )
Converting the 5d wavefunction of gold to a smoother pseudowavefunction results in a dramatic reduction in the required basis set size for converged calculations.
- B.A. Chemistry and Physics, Summa Cum Laude, Harvard University (1986)
- ONR Graduate Fellow, Massachusetts Institute of Technology (1986-1989)
- JSEP Graduate Fellow, Massachusetts Institute of Technology (1990-1992)
- Ph. D. Physics and Chemistry, Massachusetts Institute of Technology (1992)
- IBM Postdoctoral Fellow, University of California at Berkeley (1992-1994)
- Assistant Professor of Chemistry, University of Pennsylvania (1994-2000)
- Associate Professor of Chemistry, University of Pennsylvania (2000-2006)
- Professor of Chemistry, University of Pennsylvania (2006-present)
- NSF CAREER Award (1997-2001)
- Alfred P. Sloan Foundation Fellow (1998-2000)
- Dreyfus Teacher-Scholar Award (1999-2004)