A density functional theory study of poly(vinylidene difluoride) crystalline phases

The structure and energetics of crystalline phases of poly(vinylidene difluoride) were investigated using density functional theory (DFT). In particular, we present data on non-polar analogues of the β and γ phases that have not yet been experimentally characterised. The results from a variety of exchange and correlation functionals were compared and it was found that van der Waals (vdW) interactions have an important effect on the calculated crystal structures. While the relative phase energies were not strongly dependent on the functional, the cohesive energies were significantly affected