Vibronic solitons in a (nearly-) degenerate electronic system along a   1-D chain
  We consider the formation and stability of the vibronic polaron arising in a degenerate or nearly degenerate electronic system coupled to an appropriate vibrational mode. We define the electron-phonon coupling as a mixing of the electronic states by the phonon mode. Our investigation is similar to that carried out recently by Dennis Clougherty though by introducing a different coupling operator. This extends the vibronic coupling range beyond the limits set by the difference in electronic density of the progenitor bands thereby widening the applicability range of the coupled soliton. 
Mladen Georgiev