Energetics of the dipole flip-flop motion in a ferroelectric polymer chain
Document Type Article
Published by American Institute of Physics. J. Chem. Physics 126, 124908 2007. ©2007 American Institute of Physics. Permission to use. http://jcp.aip.org/.
The authors report on a study of dipole flip-flop “local” transition in ferroelectric polyvinylidene fluoride [P(VDF)] chains, using total energy calculation based on the density functional theory. The calculated results indicate that a simple flipping of a single electric dipole moment is energetically allowed. Furthermore, such a flipping involves no change either in bond length, bond angle, or the orientation of the chain. The calculations also show that on a thin film of ordered chains, strong dipole interactions existing in [P(VDF)] could cause modulation of the dipole orientation thus forming superlattices on [P(VDF)] films. These results are in good agreement with recent scanning tunnel microscope experimental measurements. Furthermore, our calculations show that partial flipping may also exist and extend over a length of several monomers during the flip-flop transition.