Numerical investigation of a molecular switch based on conformational change, with the inclusion of contacts

Although very significant difficulties have so far prevented their usage in practical applications, single-molecule devices are still considered the ultimate step in the scaling-down process of electronic circuits. One of the possible, proposed approaches to molecular-scale electronics consists in replicating the classical architecture based on three-terminal devices, which has so far been so successful with CMOS technology. However, it has been shown that modulation of molecular conductance via a purely electrostatic effect (such as in field-effect transistors) is not viable according to P. Damle (2002), and that, in order to obtain a reasonable modulation of conductance, either mechanical deformation of otherwise induced conformational changes are necessary. In this paper, we present our investigation of this latter approach, focusing on a class of molecules that may allow the implementation of switching functionalities. Switching is obtained by means of the action of a transverse electric field which induces a conformational change, thereby altering the transparency of intramolecular barriers and, as a result, the conduction state of the molecule.