Creation and mobility of self-trapped electronic states in nonlinear chains

We study the formation and mobility of self-trapped electronic states in a nonlinear one-dimensional lattice subjected to an electric-field. The nonlinearity arises from the electron-lattice coupling and the electric field is time-dependent. We show that the nonlinearity is a mechanism able to provide motion to the centroid of a delta-like wave-packet when subjected to an electric field, in contrast with the behavior of linear systems. With the co-existence of the electric field and electron-lattice interaction, the constitution of mobile self-trapped states is possible. The phase diagram reveals a rich phenomenology in which the mobility of self-trapped electronic states can exhibit an unidirectional branch migrating to the left or the right side of the chain. For weak nonlinearities, an analytical expression obtained from a semi-classical approach describes the dynamics of self-trapping states. In a strong electron-lattice regime, the wave-packet develops a self-trapped regime in which it remains fully localized at the initial site. Thus, we offer the proper tunning of electric field for the management of the creation and mobility of self-trapped electronic states through the lattice.