We develop and apply quantum-chemical methods for predicting spectroscopic properties of complex molecular systems, ranging from transition-metal catalysts
to biological molecules as well as functional materials and from X-ray spectroscopy through optical (UV/Vis) and vibrational spectroscopy to nuclear-magnetic and electron-spin resonance (NMR and ESR) spectroscopy. Our method development in this area is driven by challenging experimental problems and novel spectroscopic experiments.