Toward chemical accuracy in the computation of NMR shieldings: the PBE0 model

We present an analysis of NMR shieldings computed with a new parameter-free density functional model (PBE0) obtained combining the so-called PBE generalized gradient functional with a predefinite amount of exact exchange. A number of organic molecules as well as some transition metal oxo complexes have been considered as benchmark systems. The results obtained for 1H, 13C, 15N and 17O chemical shieldings are better than those delivered by the most reliable functionals including heavy parametrization and are competitive with those provided by low-order many-body perturbation techniques. The way in which the functional is derived and the lack of empirical parameters fitted to specific properties make the PBE0 model a widely applicable method for quantum chemistry.