Modeling controlled propagation of molecular polarization induced by wave-packet dynamics

We study the propagation of molecular polarization induced by a local excitation and its motion on the one-dimensional molecular array adsorbed on the host material. The local excitation can be either an electron wave packet or an exciton in a given molecular complex. It is found that there exist three different kinds of propagation of molecular polarization-two kinds of ballistic propagation and one diffusive propagation-depending on the values of ω0 /t and g/t, where ω0 is the excitation energy of polarization, t the electron (or exciton) hopping, and g the coupling between electron and polarization. Ballistic propagation can be understood as a bare electron's motion, while diffusive propagation implies the formation of a massive polaron. In a realistic situation, a propagating electron can be captured with a finite probability via tunneling through the adlayer energy barrier into the host material. Such effects of tunneling on the polarization propagation are investigated to examine the possibilities or limitations for controlling an array of polarization. Finally, we discuss the recent implementation of the scanning tunneling microscope (STM)-induced polarization of functional molecular nanostructures within our framework.