Recent observations confirming the presence of the protein-forming amino acid glycine in comets lend support to cometary impact as a possible source for delivering simple amino acids to early Earth. Little is known regarding the survivability or reactivity of glycine during impacts, especially considering that condensed phase chemistry at extreme conditions and can lead to the formation of new products through unusual synthetic routes. Quantum-based molecular dynamics (QMD) simulations are a useful atomistic modeling tool to predict chemistry that is difficult and expensive to isolate through laboratory experiments. With QMD, we explore how glycine reacts under the extreme temperatures, pressures, and shear states reached in shock impacts and other geological processes on early Earth and other planets and moons. Conditions typical of cometary impacts are found to prompt the rapid transformation of glycine into more complicated aromatic molecules. Shearing forces under more moderate compressive loads are predicted to drive formation of polypeptides and large oligomers. Our studies provide a "bottom-up" methodology and prospectus for predicting possible prebiotic chemistry under extreme conditions and help determine feasible chemical pathways towards chemicals needed for the origins of life.
Speaker: Matt Kroonblawd, Lawrence Livermore National Lab
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