Energetics of H2O encapsulated in fullerenes under an electric field

Based on first-principles total energy calculations, we analyze the dipole energy U = − d centerdot E of a water molecule encapsulated in fullerene isomers from C60 to C80, all of which satisfy the isolated pentagon rule. Our calculations show that the dipole energy exhibits unusual features not expected for an isolated water molecule in vacuum. The dipole energy depends sensitively on the electronic structure of fullerenes and their cage network topology when situated in an external electric field. We also demonstrate that the electrostatic potential inside the fullerene exhibits an anisotropic feature with respect to the applied field