An implementation of core level spectroscopies in a real space Projector Augmented Wave density functional theory code

► We describe an efficient implementation of core-electron spectra in a real-space-grid PAW framework. ► The importance of an absolute energy-scale is emphasized and we describe how this can be obtained. ► We show computed X-ray absorption spectra for gas phase H2O, diamond, and CO/Ni(1 0 0). ► We compute and discuss X-ray emission spectra for CO/Ni(1 0 0).