A series of density functional calculations of the structural and electronic properties of all six different fluorinated polyethylenes with several different dihedral angles are performed using two different local density approximations (LDA's), the Gaspar-Kohn-Sham and the Perdew-Zunger ones. The geometrical parameters are optimized simultaneously for the stable conformation of poly(tetrafluoroethylene) and poly(difluoroethylene). The torsional potential curves for all the poly(fluoroethylene)s show an absolute minimum at dihedral angles other than 180 degrees, corresponding to a nonplanar conformation. For poly(difluoroethylene), the absolute minimum is found at the gauche form. The valence and conduction bands as well as the Mulliken populations are calculated and compared with other theoretical calculations and experimental results.