Validating atomistic models of the structure and dynamics of water interacting with various solutes is key to expanding our understanding of this ubiquitous solvent. We do this by connecting molecular dynamics simulations (both classical and quantum) of aqueous solutions with first-principles DFT-based simulations of corresponding near-edge x-ray absorption spectra. Our interpretations provide clear assignment of both strong and weak interactions through their impact on molecular conformation and the associated electronic excited states probed by x-ray photons. Recently, we have successfully revealed subtle details of salt interactions with model proteins - both hydrophilic and hydrophobic. We have also explored and characterized the pH-driven chemistries of the geological carbon cycle, which converts gaseous carbon dioxide to dissolved carbonates, and the conversion of borohydride anions to borohydrates and boron oxides which occurs in novel hydrogen fuel cells. Particular note is made of the role of symmetry in defining clear distinctions between the spectra of each chemical species and how this might be exploited in further (potentially ultrafast) studies as a flag for chemical conversion.

Simulating X-ray signatures of interactions in aqueous solutions from first-principles

243rd National Meeting (2012)

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