Information based structure determination of amorphous carbon

In this talk, we offer large and realistic models of amorphous carbon spanning densities from 0.95 g/cc to 3.5 g/cc . The models are designed to agree as closely as possible with experimental diffraction data while simultaneously attaining a local minimum of a density functional Hamiltonian. The structure varies dramatically from interconnected wrapped and defective sp2 sheets at 0.95 g/cc to a nearly perfect tetrahedral topology at 3.5 g/cc . Force Enhanced Atomic Refinement (FEAR) was used and is shown here to be computationally superior and more experimentally realistic than conventional ab initio melt quench methods. We thoroughly characterize our models by computing structural, electronic and vibrational spectra. The vibrational density of states of the 0.95 g/cc model is strikingly similar to monolayer amorphous graphene. Our sp2 /sp3 ratios are close to experimental predictions where available, a consequence of compelling a satisfactory fit for pair correlation function.

The authors are thankful to the NSF under Grant Number DMR 1506836. We acknowledge the financial support from Condensed Matter and Surface Science (CMSS) at Ohio University.