Bond-Order-Wave versus Spin-Density-Wave Dimerization in Polyacetylene
The dimerization of polyacetylene is studied in the framework of a distance dependent Hubbard Hamiltonian for the valence π electrons. The underlying one-dimensional many-body problem is solved numerically using the density matrix renormalization group (DMRG) method and the resulting ground-state energy is optimized in order to determine the dimerization δ and the average bond-length . The strength of the Coulomb repulsion U/t is varied from the uncorrelated or Hückel limit all over to the strongly correlated or Heisenberg case. While is not significantly affected by the value of U/t, δ shows a remarkable non-monotonic behavior. The differences between the bond-order-wave (small U/t) and the spin-Peierls (large U/t) regimes are discussed.
KeywordsNear Neighbor Coulomb Repulsion Infinite Chain Ethylene Molecule Density Matrix Renormalization Group
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