Excess electron motion in a molecular chain and nonlinear rate equations

Abstract

The nonlinear quantum dynamics of the simultaneous transfer of two electrons in a molecular chain are studied. The discussion concentrates on the interplay between the mutual Coulomb interaction and the dephasing of the electronic wave function. A nonexponential redistribution of the electronic occupation probability has been obtained by the numerical solution of appropriate equations of motion of the electronic density matrix. Such a behavior can be explained in deriving a set of nonlinear rate equations which take into account the shift of the electronic site energies due to the mutual Coulomb interaction. This approximate description agrees well with the exact one for dephasing times equal and smaller than the coherent transfer time.