A van der Waals density functional theory study of poly(vinylidene difluoride) crystalline phasesF. Pelizza, B.R. Smith and and K. JohnstonEur. Phys. J. Special Topics, 225 8-9 (2016) 1733-1742DOI: https://doi.org/10.1140/epjst/e2016-60133-8