Vibrational frequencies and thermodynamic properties in ADF and BAND are calculated with the harmonic approximation from the second derivatives. Analytic frequencies are available for GGAs in ADF, and are computed numerically otherwise. IR spectra and vibrations can also be calculated with our semi-empirical software modules DFTB and MOPAC. IR spectra and molecular vibrations are conveniently visualized with the integrated graphical interface (see Tutorial).
Raman spectra and vibrational optical activity
With ADF, static and resonant Raman spectra can also be calculated, as well as vibrational circular dichroism (VCD) and (Resonance) Raman Optical Activity (R)ROA.
For the vibrational analysis of a small part of a large systems, the mobile block Hessian (MBH) method can be used, which treats spectator parts as rigid blocks.