The molecular force field of 4-fluorostyrene: an insight into its vibrational analysis using inelastic neutron scattering, optical spectroscopies (IR/Raman) and theoretical calculations

This paper reports for the first time a molecular force field of the 4-fluorostyrene molecule making a joint use of data from optical spectroscopies (IR/Raman), neutron scattering (INS) and theoretical calculations, ab initio (HF, MP2) and DFT with different basis sets. Harmonic molecular force fields were calculated following two different procedures, scaling and refinement. Also, proposed is a complete set of valence force constants obtained via the so-called pure vibrational force field. In a parallel way, some structural features such as the vinyl torsion barriers, the C=C vinyl bond, and Ph-vinyl C=C bond, among others, were analysed. A comparison with available experimental data for some standard and related molecules allows conclusions about the aromaticity of these systems.