Electron-Lattice Relaxation, and Soliton Structures and Their Interactions in Polyenes

Abstract

Density matrix renormalization group calculations of a suitably parametrized model of long polyenes (polyacetylene oligomers), which incorporate both long range Coulomb interactions and adiabatic lattice relaxation, are presented. 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. The ${1}^{1}{B}_{u}^{\ensuremath{-}}$ state forms an exciton polaron and has a very small relaxation energy. The relaxed energy of the ${2}^{1}{A}_{g}^{+}$ state lies below that of the ${1}^{1}{B}_{u}^{\ensuremath{-}}$ state. The soliton/antisoliton pairs are bound.