Effects of alternating coulomb and resonance interactions in correlated one-dimensional diatomic systems

The diatomic-chain model of mixed-stack molecular crystal is studied accounting for the electron correlation and lattice relaxation. Energetics, Peierls distorsion and charge transfer are calculated by the use of optimized-germinal technique. The realistic case of Hubbard electron repulsion on donors stronger than on acceptors is considered, it is shown that taking into account this difference improves the predictions of dimerization properties. The limiting case of correlated donor-acceptor dimers that interact only through Coulomb field is considered analytically; it is found that interdimer hopping is essential for adequate predictions of characteristics of neutral-to-ionic phase transition. Calculations of broken-symmetry states of the correlated chain show that metastable solitons with excitation energy close to transfer integral are possible near the phase transition point