Paul Siders

Formation of graphite from hydrothermal fluids may be catalyzed by mineral surfaces. Catalysis, if it occurs, likely requires adsorption of reactants or intermediates. Physisorption may suffice. Reactants are the components of a C-O-H hydrothermal fluid: methane, water, and carbon dioxide. Likely reaction intermediates are small molecules and resonance-stabilized radicals. Minerals associated with hydrothermal graphite deposits include pyrite, quartz, and olivine. Of these, pyrite catalyzes graphite formation and quartz does not. Catalysis by iron-magnesium minerals has been suggested. This project studies adsorption from a C-O-H fluid onto one stable and simple face of pyrite, quartz, and an iron-magnesium olivine. The method will be Car-Parrinello molecular dynamics of the mineral faces and the fluid, including intermediates as solutes. Supercritical conditions will be explored, starting with 773 K and 4 kbar. Initial simulations will examine possible physisorption of water, carbon dioxide, and methane.