Stability, phonon dispersion and specific heat of solid poly(vinyl alcohol) using density functional theory

- We reported first principles calculation of poly(vinyl alcohol) in orthorhombic and monoclinic phase.
- Electronic band structure and phonon dispersion curves are calculated in both the phases.
- Lowest energy minimum is in case of orthorhombic phase hence, structure is more favourable to orthorhombic phase.
- Specific heat shows general trends as observed in other polymers.

The present paper reports a systematic theoretical study of structural, electronic, vibrational and thermal properties of solid poly(vinyl alcohol) (PVA) in the orthorhombic and monoclinic structures. Our results on phonon dispersion curves confirm that PVA is dynamically stable in both orthorhombic and monoclinic structures as claimed by the X-ray diffraction study. However, total energy is minimum in the case of orthorhombic structure and hence orthorhombic is more favorable phase of PVA. We also report the electronic band structure for PVA in both structures and obtained a good agreement between present and available data. The dielectric constant has also been reported and discussed. We have also calculated the temperature dependent specific heat at constant volume, Cv and discussed its behavior. There is a reasonably good agreement between the experimental and our calculated data.