Comparison of polarization and Born effective charges in   alternatively-deflected zigzag and planar-zigzag $beta$-poly(vinylidene   fluoride)
  A density-functional study of the alternatively-deflected zigzag structure for the beta-phase of poly(vinylidene fluoride) or (-CH2-CF2-)n is presented. Structure, polarization and effective charges have been determined. Using lattice constants and atomic positions transformed from experiment, the space group for the alternatively-deflected zigzag structure was found to be Cc2m (C2v 16), in agreement with previous studies. We find a polarization for the alternatively-deflected structure identical to that of the planar-zigzag structure with small changes in the accompanying effective charges. 
Nicholas J. Ramer, Kimberly A. Stiso