On the ionization energy of HfO.

Using a newly developed relativistic pseudopotential and a series of correlation consistent basis sets for Hf, the ionization energy of HfO and the spectroscopic properties of the HfO(+) cation have been determined in coupled cluster calculations. After accounting for basis set incompleteness, outer-core correlation, the pseudopotential approximation, and higher order electron correlation effects, excellent agreement with recent experimental measurements is obtained.