  The Hamiltonian describing a system of strongly correlated electrons coupled
to dispersionless phonons was solved numerically for a ring of 8 atoms using
the density matrix renormalization group (DMRG) method. It was found that
electron correlation and electron-phonon coupling compete against each other,
and strong electron correlations suppress the charge-ordered insulating state.
This allows extended polarons to form in the strong electron-phonon coupling
regime. It is shown that in this regime two polarons may form a pair via phonon
mediated charge-fluctuation interaction. Based on the results we propose a
novel mechanism of hole pairing. This mechanism could be relevant to High-Tc
cuprates.
