  We discuss the behavior of a two-level system coupled to a quantum dot
contacted by superconducting source/drain electrodes, representing a simple
model for the conformational degree of freedom of a molecular dot or a break
junction. The Josephson current is shown to induce conformational changes,
including a complete reversal. For small bias voltage, periodic conformational
motions induced by Landau-Zener transitions between Andreev states are
predicted.
