Figure 6

BLYP/DNP calculation[21] of pyrene and a fragment of the soot model.[1] The plotted spheres define the atomic radii of each element. Note that the two do not overlap, but there is not room for another molecule between the sheets. The plan view illustrates that the aromatic rings are offset to place carbon atoms of the pyrene molecule above the holes in the aromatic rings of the soot fragment. The density functional theory calculations do not show an energy minimum commensurate with the observed spacing in soot or with the MD simulations. Graphics generated with CrystalMaker.[34]