Electron self-trapping on a nano-circle
  We study the self-trapping of quasiparticles (electrons, holes, excitons, etc) in a molecular chain with the structure of a ring, taking into account the electron-phonon interaction and the radial and tangential deformations of the chain. A discrete system of equations is obtained and solved numerically. The analytical solutions for the wave function of a quasiparticle and for the molecule displacements that determine the distortion of the ring, are also obtained and solved in the continuum approximation. The numerical solutions of the system of discrete nonlinear equations reveals several regimes of quasiparticle localisation in the chain which depend on the values of the parameters of the system. It is shown that the transversal deformation of the chain favours the formation of a soliton. 
L.S. Brizhik, A.A. Eremko, B. Piette W. Zakrzewski