Nonlinear excitations dynamics in molecular switches

The charge transfer on a single polyacetylene chain is studied with impurities and added molecules working as switches. The chain is modeled by a Su-Schrieffer-Heeger (SSH) type Hamiltonian extended to include the effects of an external field and the parameters of the switching molecules. The equations of motion of the system are numerically integrated and the time evolution of the charge on the chain is analyzed. The charge transfer through the sites that work like a switch is considered. Two basic types of molecular switches are studied: pair of donor-acceptor molecules embedded in the polymer chain and bonded to the chain. The main differences between these two models of switches are determined. The influence of the parameters of the molecules (site energy and bond strengh) on the charge transfer as well as the changes they must undergo to characterize the molecular switch is determined. The role of the length of separation between the sites where the donor and acceptor molecules bond is clarified.