Ab Initio Molecular Orbital Calculation on a Condensed-Substance Model System for the Water Sorption Phenomenon of Polymers: Poly (vinyl fluoride) Model

Abstract

The normal vibration calculations were made by means of the Ab Initio molecular orbital (MO) calculation method, for a condensed-substance model (the system of many molecules) composed of four poly (vinyl fluoride) (PVF) oligomers and a water molecule. The calculation results explained the shift of the infrared spectra observed for water molecules sorbed into PVF. That is, the calculated stretching frequencies ν (OH) of water molecules shifted 28-32cm^-1 to lower wavenumbers. Moreover, the present results confirmed that their lowering shifts originate from the structural changes of water molecules under the intermolecular interactions.