Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5186224 | Polymer | 2006 | 6 Pages |
The structure of the non-polar α-phase of poly(vinylidene fluoride) (PVDF) is determined by density-functional methods. We find very good agreement between our relaxed structure and that of previous X-ray diffraction studies. Using the relaxed structure, we have determined the infrared and Raman frequencies for the material using density-functional perturbation theory. The resulting frequencies are in excellent agreement with experiment and are comparable in accuracy to semi-empirical values for most absorbencies. In addition, we find a better agreement to experiment than a previously reported Hartree-Fock determination of vibrational frequencies in finite isolated PVDF chains. The low-frequency portion of our spectra (50-300 cmâ1) shows better agreement with experimental values than the same frequencies found semi-empirically. Improved accuracy in this frequency range will aid in modeling phase transitions and dielectric response in PVDF.