Optical characterization of ground states of polyacene
  We investigate the ground-state properties of polyacene in terms of an extended Peierls-Hubbard Hamiltonian with particular emphasis on its structural instability of two types: double bonds in a "cis" pattern and those in a "trans" pattern. Calculating the polarized optical conductivity spectra within and beyond the Hartree-Fock scheme, we reveal a striking contrast between the "cis" and "trans" configurations. The two Peierls-distorted states are almost degenerate in their energetics but quite distinct in their optics. 
Shoji Yamamoto