Todd J. Martínez
Gutgsell Chair in Chemistry
Professor Martínez was awarded the B.S. in chemistry by Calvin College in 1989 and the Ph.D. in chemistry by the University of California (Los Angeles) in 1994. He was a Fulbright Fellow at the Fritz Haber Institute for Molecular Dynamics in Jerusalem, Israel and a University of California Presidential Postdoctoral Fellow at UCLA for two years prior to joining the faculty at University of Illinois in 1996. His research interests are in theoretical chemistry with particular emphasis on electronic structure and molecular dynamics.
Research
Quantum chemistry traditionally solves the time-independent, zero temperature electronic Schrödinger equation, assuming separability of the electronic and nuclear degrees of freedom. This provides potential energy surfaces for use in molecular dyna-mics simulations to understand finite temperature and time-dependent effects. We take a different approach—extending quantum chemistry into the time domain, bridging the gap between traditional molecular dynamics (what are the atoms doing?) and quantum chemistry (what are the electrons doing?). We include quantum mechanical effects on the behavior of the electrons and the atoms by simultaneously solving the electronic and nuclear Schrödinger equations. This "ab initio multiple spawning" (AIMS) method opens exciting possibilities in modeling chemistry. Rearrangement of chemical bonds, tunneling, and dynamics on multiple electronic states are all treated correctly without ad hoc assumptions.
We are especially interested in electronic excited states, where the assumption of electron–nuclear separability breaks down. Using AIMS, we investigated fundamental photochemical reactions—quenching of excited metal atoms, cis–trans isomerization in ethylene and butadiene, and ring-opening of cyclobutene. In each case we found that conventional explanations required modification. This research furthers the understanding of complex molecular dynamics on multiple electronic states during photochemical reactions. Our goal is AIMS for reactions in complex environments, whether they be normal solvents (e.g., water), solid cages (e.g., zeolites), or portions of a protein. We are developing methods to address solvent effects on photochemistry and spectroscopy, with ultimate application to biologically relevant molecules such as visual pigments.
Because of tunneling effects, proton transfer reactions require quantum treatment of the nuclei. We recently performed the first ab initio molecular dynamics simulation of real-time tunneling dynamics, simulating intramolecular proton transfer in malonaldehyde. Future directions include AIMS studies of coupled electron and proton transfer reactions, which are important in biological systems and possibly for designing molecular electronic devices.
Finally, we use novel quantum chemistry methods to elucidate the function of biologically relevant metallo-proteins—currently, the reaction mechanism of cytochrome c oxidase. This final enzyme in the respiratory cycle reduces oxygen. We investigate the nature of spin coupling between transition metal centers, the role of tyrosyl radicals in the mechanism, and the coupling of electron transfer and proton transfer in the enzyme active site.
Publications
"Ab Initio Molecular Dynamics of Excited State Proton Transfer Using Multireference Perturbation Theory, J. D. Coe," B. G. Levine, and T. J. Martínez, J. Phys. Chem., 111, 11302 (2007).
"Conformationally controlled chemistry: Excited state dynamics dictate ground state dissociation", M. H. Kim, L. Shen, H. Tao, T. J. Martínez, and A. G. Suits, Science, 315, 1561 (2007)."Isomerization Through Conical Intersections", B. G. Levine and T. J. Martínez, Ann. Rev. Phys. Chem., 58, 613 (2007).
"QTPIE: Charge Transfer with Polarization Current Equalization. A fluctuating charge model with correct asymptotics", J. Chen and T. J. Martínez, Chem. Phys. Lett., 438, 315 (2007).
"Ab Initio Molecular Dynamics and Time-Resolved Photoelectron Spectroscopy of Electronically Excited Uracil and Thymine", H. R. Hudock, B. G. Levine, A. L. Thompson, H. Satzger, D. Townsend, N. Gador, S. Ullrich, A. Stolow, and T. J. Martínez, J. Phys. Chem., 111A, 8500 (2007).
"Multicentered Valence Electron Effective Potentials: A Solution to the Link Atom Problem for Ground and Excited Electronic States, P. Slavicek and T. J. Martínez, J. Chem. Phys., 124, 084107 (2006).
"Insights for Light-Driven Molecular Devices from Ab Initio Multiple Spawning Excited-State Dynamics of Organic and Biological Chromophores, T. J. Martínez, Acc. Chem. Res., 39, 119 (2006).
"Conical Intersections and Double Excitations in Time Dependent Density Functional Theory, B. G. Levine, C. Ko, J. Quenneville, and T. J. Martínez, Mol. Phys., 104, 1053 (2006).
"Competitive Decay at Two and Three-State Conical Intersections in Excited State Intramolecular Proton Transfer, J. D. Coe and T. J. Martínez, J. Amer. Chem. Soc., 127, 4560 (2005).
"Helix Switching of a Key Active Site Residue in Cytochrome cbb3 Oxidases, J. Hemp, C. Christian, B. Barquera, R. B. Gennis, and T. J. Martínez, Biochemistry, 44, 10766 (2005).
"Using Meta-Conjugation to Enhance Charge Separation versus Charge Recombination in Phenylacetylene Donor-Bridge-Acceptor Complexes, A. L. Thompson, T.-S. Ahn, K. R. J. Thomas, S. Thayumanavan, T. J. Martínez, and C. J. Bardeen, J. Amer. Chem. Soc., 127, 16348 (2005).
Awards
- John D. and Catherine T. MacArthur Fellow
- University Scholar, UIUC
- Helen Corley Petit Scholar
- Fulbright Fellowship
- U. C. President's Postdoctoral Fellow
- NSF CAREER Award
- Research Innovation Award
- Alfred P. Sloan Fellowship
- Packard Fellow
- Beckman Young Investigator Award
- Dreyfus Teacher-Scholar Award
