Gauging the Performance of Density Functionals for Lanthanide-Containing Molecules

Several density functional approaches have been considered for their ability to predict enthalpies of formation and bond dissociation energies for lanthanide-containing molecules. To enable comparison with experiment, the Ln54 set, introduced here, is compiled to include lanthanides both in the common 3+ oxidation state as well as in more exotic oxidation states. Due to the magnitude of the experimental uncertainties a "lanthanide chemical accuracy" of 5.0 kcal mol(-1) is proposed. The density functionals considered span the full range of complexity from LDA through double hybrids. The performance of the density functionals is assessed for each class of lanthanide-containing molecules and for the Ln54 molecule set overall. In general, hybrid functionals perform worse than functionals without exact exchange, and TPSS performs the best overall for the Ln54 set with a MAD of 19.2 kcal mol(-1) and MSD of -1.9 kcal mol(-1).