A theoretical investigation of the near-edge X-ray absorption spectrum of hexa-peri-hexabenzocoronene

The near-edge X-ray absorption spectrum of hexa-peri-hexabenzocoronene has been simulated by density functional theory techniques using transition state and full core hole potentials. The total spectrum is found to be a composition of multiple structure in the subspectra of the symmetry unique carbons, rather than by chemically shifted single π∗ transitions. This quite `fullerene-likeʹ behavior, with only minor reminiscence of either graphite or benzene spectral features, is used to argue that long-range effects must be important to build up the dominating single excitonic π∗ feature in graphite.