Evolution of amorphous carbon across densities: An inferential study

Abstract

In this paper, we offer large and realistic models of amorphous carbon spanning densities from 0.95 g/cm 3 to 3.5 g/cm 3 . 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 sp 2 sheets at 0.95 g/cm 3 to a nearly perfect tetrahedral topology at 3.5 g/cm 3 . 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/cm 3 model is strikingly similar to monolayer amorphous graphene. Our sp 2 /sp 3 ratios are close to experimental predictions where available, a consequence of compelling a satisfactory fit for pair correlation function. arXiv:1712.01437v1 [cond-mat.dis-nn]

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