Theory of Molecular Conformational Switching

We have investigated stability and current switching as a function of conformational change in tolane molecule by ab initio Hartree-Fock and density functional theory approaches. The planar conformation of the molecule in which the two benzene rings are coplanar is calculated to be more stable than a twisted conformation. The current ($I)$ with respect to the applied external potential ($V)$ increases from minimum to maximum as the two $\pi $-rings become planar, suggesting the ``ON'' and ``OFF'' mechanism of the molecular switch at planar and perpendicular conformations, respectively.