First-principles calculation of the phonon spectrum of MgAl2O4 spinel

The phonon spectrum of a ${\mathrm{MgAl}}_{2}{\mathrm{O}}_{4}$ spinel has been calculated from first principles using density-functional theory. The spinel was perfectly ordered with space group $\mathrm{Fd}3\ifmmode\bar\else\textasciimacron\fi{}m.$ The five Raman active and four infrared active modes allowed by symmetry are unambiguously identified. Agreement with available Raman, infrared, and inelastic neutron scattering data is good. The fifth Raman mode (missing in experiment) is located at $570 {\mathrm{cm}}^{\ensuremath{-}1}.$