Electron-lattice relaxation, and soliton structures and their interactionsin polyenes

Density matrix renormalization group calculations of a suitably parametrize d model of long polyenes (polyacetylene oligomers), which incorporate both long range Coulomb interactions and adiabatic lattice relaxation, are prese nted. The 1(3)B(u)(+) and 2(1)A(g)(+) states are found to have a 2-soliton and a 4-soliton form, respectively, both with large relaxation energies. Th e 1(1)B(u)(-) state forms an exciton polaron and has a very small relaxatio n energy. The relaxed energy of the 2(1)A(g)(+) State lies below that of th e 1(1)B(u)(-) state. The soliton/antisoliton pairs are bound. [S0031-9007(9 9)08504-X].