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Research Abstracts Online
January 2008 - March 2009

Gustavus Adolphus College
Department of Chemistry

PI: Jonathan M. Smith

Simulation of Resonance Raman Spectra Using Consistent Excited State Gradients and Solvation

Resonance Raman spectra contain detailed information about excited state molecular dynamics, molecular conformation, and, often, local solvent environment. The simulation of resonance Raman spectra requires detailed ground and excited electronic state quantum mechanical calculations, but can yield rich details about the molecular system under study should the simulation and experiment show quantitative agreement.

Solvent vibrational frequency shifts are often difficult to predict and are an important step in correct simulation of resonance Raman spectra. This project seeks a consistent treatment of ground state and excited states through the use of new density functional theory functionals including M06L, TDDFT, and CASPT2 excited state calculations to improve on current methodologies in producing the excited state gradients and optimized ground state structures with Hessians. The resonance Raman spectra under consideration are for small model compounds including imidazole and single amino acids in aqueous solution. Resonance Raman spectra can be very sensitive to solvent effects and thus can reveal details about local solvent environment. Detailed simulation must therefore include a good treatment of solvent. Simulation of spectra will be refined through examination of the SM6/SM7 solvation model coupled to explicit solvation.