Symmetrised quantum-mechanical force-fields and INS spectra: s-triazine, trichloro-s-triazine and pyrazine

Abstract

A vibrational analysis of the Inelastic Neutron Scattering (INS) spectra of s-triazine, trichloro-a-triazine and pyrazine has been carried out starting from different ab initio calculations levels (HF/3-21G, HF/6-31G ∗ and MP2/6-31G ∗). Resulting force fields were transformed to the symmetry-coordinate system and refined to the observed INS spectral profile. Similar final force fields result regardless of the level of the ab initio calculation. The importance of INS intensities in determining the values for the interaction constants is demonstrated.