Lawrence Livermore National Labs
LAMMPS Driven Quantum Simulations of Prebiotic Chemistry in Impacting Icy Materials
Potentially life-building compounds (e.g., amino acids, peptides, etc.) can be produced on a planet via abiotic sources and were consequently likely present before the emergence of life on early Earth. Protein forming amino acids could have been delivered by astrophysical bodies originating externally from the planet, such as impacting meteorites, comets, and interstellar dust particles. Shock compression due to impact has been shown to result in the synthesis of amino acids from raw materials, as well as the formation of extended C-N bonded networks similar to peptide chains. However, the role these materials played in the in the emergence of life remains an open question, in part because little is known about their survivability and reactivity during extreme pressures and temperatures.
To this end, we have used quantum simulations driven by LAMMPS through a Fortran/C++ interface to explore the role of extreme conditions in the emergence of organization of amino acids. We have employed a force matching semi-empirical quantum simulation method to study oblique impacts of aqueous glycine solutions at conditions of up to 50 GPa and 3000 K for close to chemical equilibrium timescales. We find that these elevated conditions induce the formation of glycine-oligomeric structures with a number of different chemical moieties such as hydroxyl and amine groups diffusing on and off the C-N backbones. The C-N backbones of these structures generally remain stable during cooling and expansion, yielding a wide variety of functionalized nitrogen containing polycyclic aromatic hydrocarbons (NPAHs). The inclusion of nitrogen into an aromatic system and the subsequent growth of these compounds can fill the mechanistic missing link between nitrogen bearing acyclic molecules and prebiotic nucleobases along with vitamins found in meteorites. Our results will help guide future experimentation by providing both a possible synthetic mechanism as well as a catalogue of possible chemical products to be investigated for these systems.
Nir Goldman received a B.S. in Chemistry from Yale University in 1997 and a Ph.D. in Physical Chemistry from the University of California, Berkeley, in 2003. He then joined Lawrence Livermore National Laboratory (LLNL) as a post-doctoral researcher, where he was promoted to the position of staff scientist in 2006. His current research interests involve the development of novel approaches to classical and quantum molecular dynamics simulations of chemical reactivity within condensed matter, including materials under extremely high pressures and temperatures and the astrobiological synthesis of life-building compounds under extreme thermodynamic conditions.