Research Papers in Physics and Astronomy

 

Date of this Version

June 2004

Comments

Published in Physical Review B 69, 235106 (2004) (6 pages)
URL: http://link.aps.org/abstract/PRB/v69/e235106
doi:10.1103/PhysRevB.69.235106 Copyright 2004 American Physical Society. Used by permission.

Abstract

We present a systematic study of the dipole alignment in the polyvinylidene fluoride (PVDF) films using first-principles total energy calculations. The ground state of a single layer film is a state with all the dipoles lying parallel to the film plane. This can also be explained by a dipole-dipole interaction model. The induced mirror charges on conducting substrates or substrates with a non-negligible dielectric response play an important role in aligning the polarization perpendicular to the film. From fitting the ab initio calculations, we obtain an effective monomer dipole moment of 4.7×10–30 C m. This corresponds to a spontaneous polarization of 0.087 C/m2, which agrees with other theoretical and experimental values. Simulation reveals a more complex behavior for molecular bilayer. We studied three molecular multilayer structures to compare the total energy and model calculations. Close examination of these results provides a better understanding of PVDF film growth and dipole orientation on different substrates.

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