Exploring potential energy surfaces for strong field chemistry, ion dynamics and bio-organic chemistry

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H. Bernhard Schlegel of Wayne State University is supported by an award from the Chemical Theory, Models and Computational Methods program in the Chemistry Division to explore projects in strong field chemistry, ab initio molecular dynamics, bio-organic systems, and reaction path optimization. Explicitly, integration of time dependent configuration interaction (TD-CI) and density functional theory will be compared for modeling molecules interacting with short, intense laser pulses. Different methods for simulating strong field ionization will be assessed. TD-CI simulations with field-dependent states and improved methods for integrating ab initio classical trajectories in strong fields will be developed. Standard and long-range corrected functionals will be compared for classical trajectories in strong laser fields. These ab initio molecular dynamics methods will be used to study the kinetic energy distribution of protons in strong field fragmentations, and H(+) migration and H3(+) formation from molecules interacting with intense laser fields. Studies of bio-organic systems will include redox potentials of intermediates in guanine oxidation pathways, environmental effects on nucleobase pKa's and redox potentials, guanine-thymine crosslinks and metal-promoted oxidation of guanine. To support these studies, new methods will be developed for reaction path optimization, reaction paths through seams and conical intersections, and reaction paths for bifurcating potential energy surfaces.Understanding molecular dynamics and exploring reaction pathways are key challenges in chemistry. Strong field chemistry and attosecond science address these challenges by using short intense laser pulses to probe structure and reactivity. Professor Schlegel and his team are developing new methods for simulating the behavior of molecules under these extreme conditions. The selected studies of bio-organic systems include properties and reactivity of DNA bases related to toxicity, mutagenesis and cancer. To support these studies, the researchers are developing new methods for exploring reaction paths on potential energy surfaces that will benefit many areas of chemistry which utilize molecular orbital calculations.