Panukorn Sombut did not have an easy task for this PhD work: He was the only theorist in an an experimental group, and he had to provide the basis for correctly interpreting many experimental results based on density functional theory (DFT) calculations. The systems he had to tackle were not the easiest ones for DFT, with magnetism, multi-valency and correlation complicating the calculations. Both his PhD thesis Computational Studies of Metal Oxide Surfaces as Model Single-Atom Catalysts as well as the PhD defence were awarded the best grade, which was well deserved. His success was a good reason for a celebration on the rooftop of the TU physics building.