Aggregation of carbon in an atmosphere of molecular hydrogen investigated by ReaxFF-molecular dynamics simulations

The formation of carbon and hydrocarbon molecules by aggregation of carbon in a H2 atmosphere was investigated by molecular dynamics simulations based on the Reax force field (ReaxFF). Systems of 500 carbon atoms and 1000 hydrogen molecules were simulated at different densities and temperatures from 1000 K to 2000 K. The majority of hydrocarbons formed during 4 ns of simulation time consist of four carbon atoms and less and a varying number of hydrogen atoms. Their number increases with increasing system temperature. The formation of few large hydrocarbon molecules is observed via formation of linear carbon-rich molecules. These large molecules have mainly branched structures and contain hardly any pentagons to heptagons which are typical structural elements in large hydrocarbons and carbon nanostructures.