Excited states and soliton structures

This prediction is confirmed by the numerical results shown in Fig. 7.1, which agree (up to a numerical factor of 2) with a strong coupling analysis in the continuum limit (Nakano and Fukuyama 1980) that predicts, 

Electron-phonon interactions in the absence of Coulomb interactions lead to midgap states and associated geometric lattice defects, or solitons. In this section we explore how these geometric defects change as a function of the electron-electron interaction strength. 

we examine the relaxed and vertical energies of the Pariser-Parr-Pople-Peierls model as a function of the interaction strength. These transition energies are illustrated in Fig. 7.4. We first note the crossover in the vertical energies of the and states as a function of C (as already discussed in Chapter 

5) signifying the highly correlated nature of the state at strong-coupling 

For all parameter values the relaxation energy of the l B state is modest, in contrast to the large relaxation energies of the and 2 A+ states relative 

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