Thermochemistry of FeOmHnz Species: Assessment of Some DFT Functionals.

Thermochemical data for 20 anionic, cationic, and neutral gas-phase species, including Fe0/+, FeO-/0/+/2+, FeOH0/+/2+, FeO2-/0/+, OFeOH0/+, Fe(OH)20/+, Fe(H2O)+/2+, and Fe(H2O)2+/2+ with oxidation states between +I and +IV for Fe and -I and -II for O, compiled by Schröder [ J. Phys. Chem. A 2008, 112, 13215], are used to assess the performance of the "Jacob's ladder" functionals PBE, TPSS, PBE0, and TPSSh for the SVP, TZVP, and QZVP basis sets. In addition, the BP86 and B3LYP functionals are considered. The TPSSh functional performs best. With the TZVP basis set (recommended), the mean absolute and the maximum errors are 24 and 63 kJ/mol, respectively. With 32 and 78 kJ/mol, respectively, BP86 is second best, better than PBE.