We report three types of nonplanar conformations, $\alpha$, $\beta$, and $\gamma$, for a neutral isolated oligoaniline molecule as well as for an oligoaniline with Au and Pd atoms attached at its ends. Each type of conformation has several conformers of nearly equal energies. An applied external voltage can be used to switch between conformations, producing in the process a sharp decrease of their energies. These bias voltage-induced conformational changes are a potential switching mechanism for two terminal molecular devices at the nanoscale domain. They cause the conductivity of the molecule to alternate between high and low states, compensating for the behavior of typical three-terminal devices, needed for the development of a gate-less electronics.

• Received 26 August 2006

DOI:https://doi.org/10.1103/PhysRevA.75.022511