Realistic molecular models of porous carbons obtained from Reverse Monte Carlo simulations

Keywords:
reverse Monte-Carlo, tight-binding, bond order potential, porous carbons

Abstract:
We present a simulation protocol based on Reverse Monte Carlo (RMC) which incorporates an energy constraint to model porous carbons. We use our simulation protocol to build molecular models of 3 saccharose based carbons included one activated sample. The radial distribution functions of the simulated models are in good agreement with experiment. The bond angle neighbor distributions calculated shows that the models capture the correct chemistry of the carbon atoms depending on their local environment. Using a ring connectivity analysis that we developed, we found that these atomistic models of carbons are made up of graphene segments twisted in a complex way. These graphene segments are made up of 6 carbon member rings and also contain some 5 and 7 carbon member rings. We also found that apart from the graphene segments there are some carbon chains which do not belong to any graphene segments. The intrinsic stability of our carbon structure was subsequently studied as a function of temperature using MD tight-binding simulation in the canonical ensemble. To characterize our models, we calculated the geometric pore size distribution and also simulated the adsorption of argon at 77.4 K in the models using the Grand Canonical Monte-Carlo technique.

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Nanotech 2006 Conference Program Abstract