Computational Spectroscopy Lab

Vibrational dynamics of 4-fluorobenzaldehyde from periodic DFT calculations.

Abstract

A thorough vibrational portrait of 4-fluorobenzaldehyde is presented, covering Infrared (Mid- and Far-), Raman and Inelastic Neutron Scattering (INS) spectra. Periodic DFT calculations (CASTEP) of a model 4FB crystal proved useful for vibrational assignment, yielding estimates of experimental spectra with near one-to-one correspondence – including the correct estimation of overtone and combination modes. A striking similarity among the Far-IR spectrum of liquid 4FB and that estimated based on a periodic structure indicates that the solid-liquid transition induces soft structural changes which leave most vibrational modes unaffected – except for those directly involved in Csingle bondH…O bonding, where crystal field splitting is observed.

Paulo J. A. Ribeiro-Claro, Pedro D. Vaz, Mariela M. Nolasco, Catarina F. Araujo, F.P.S.C. Gil, Ana M. Amado.