  By employing a newly developed dynamical simulation method, which is a
combination of classical molecular dynamics (MD) and the adaptive
time-dependent density matrix renormalization group (TDDMRG), we investigate
the dynamics of charge carrier transitions in trans-polyacetylene (PA) with the
inclusion of both electron-phonon and electron -electron interactions. The
calculations are performed within a modified Su-Schrieffer-Heeger (SSH) model
in which electron-electron interactions are taken into account via the
combination with extended Hubbard model (EHM). We find that removing an
electron from a trans-PA chain bearing a positively charged polaron leads to
the formation of a pair of charged solitons. Furthermore, we study the effect
of electron-electron interactions on such charge carrier transitions in
trans-PA. Our results show that increasing the on-site Coulomb interaction U
and the nearest-neighbor Coulomb repulsion V will not change the qualitative
behavior of the transition from a polaron to a soliton pair in the evolution
process but will quantitatively reduce the moving velocities of the both formed
solitons significantly and change the conditions for the soliton collisions.
