PNNL

Abstract

We have performed detailed ground and excited state calculations of pure and N-doped TiO2 rutile to model and analyze the experimentally observed UV/Vis spectrum. Using our embedding model we have performed both linear-response (LR) and real-time (RT) TDDFT calculations of the excited states of the pure and N-doped systems. We have also studied the lowest excitations using high-level active space equation-of-motion coupled cluster (EOMCC) approaches involving all single and inter-band double excitations. We compare and contrast the nature of the excitations in detail for the pure and doped systems and also provide an analysis of the excited-state density using our RT-TDDFT calculations. Our calculations indicate a lowering of the band gap and verify the role of the N3- states on the observed spectrum of N-doped TiO2 rutile as suggested by experimental findings. Both RT-TDDFT and EOMCC calculations show that the excitations in pure TiO2 are more delocalized compared with the N-doped system.