Iron oxide (FeO) is one of the classical Mott insulators, which electronic properties are determined by strong electron correlations in Fe(3d) states. I will present the results of first-principles studies on structural and dynamical properties of iron monoxide, demonstrating a strong effect of cation vacancies on phonon spectra .
Recent nuclear inelastic scattering studies revealed significant differences between the phonon density of states of FeO bulk and thin layers deposited on Pt(111). These differences have been explained on the basis of ab initio calculations. Some comparison between lattice dynamics of FeO and isostructural europium oxide (EuO) will be presented.
 U.D. Wdowik, P. Piekarz, K. Parlinski, A.M. Oleś, and J. Korecki, Phys. Rev. B 87, 121106 (2013)