title: Benchmark Calculations of Energetic Properties of Groups 4 and 6 Transition Metal Oxide Nanoclusters Including Comparison to Density Functional Theory.
abstract: The heats of formation and the normalized clustering energies (NCEs) for the group 4 and group 6 transition metal oxide (TMO) trimers and tetramers have been calculated by the Feller-Peterson-Dixon (FPD) method. The heats of formation predicted by the FPD method do not differ much from those previously derived from the NCEs at the CCSD(T)/aT level except for the CrO3 nanoclusters. New and improved heats of formation for Cr3O9 and Cr4O12 were obtained using PW91 orbitals instead of Hartree-Fock (HF) orbitals. Diffuse functions are necessary to predict accurate heats of formation. The fluoride affinities (FAs) are calculated with the CCSD(T) method. The relative energies (REs) of different isomers, NCEs, electron affinities (EAs), and FAs of (MO2)n (M = Ti, Zr, Hf, n = 1-4) and (MO3)n (M = Cr, Mo, W, n = 1-3) clusters have been benchmarked with 55 exchange-correlation density functional theory (DFT) functionals including both pure and hybrid types. The absolute errors of the DFT results are mostly less than ±10 kcal/mol for the NCEs and the EAs and less than ±15 kcal/mol for the FAs. Hybrid functionals usually perform better than the pure functionals for the REs and NCEs. The performance of the two types of functionals in predicting EAs and FAs is comparable. The B1B95 and PBE1PBE functionals provide reliable energetic properties for most isomers. Long range corrected pure functionals usually give poor FAs. The standard deviation of the absolute error is always close to the mean errors, and the probability distributions of the DFT errors are often not Gaussian (normal). The breadth of the distribution of errors and the maximum probability are dependent on the energy property and the isomer.
authors.affiliation: Department of Chemistry, The University of Alabama , Shelby Hall, Box 870336, Tuscaloosa, Alabama 35487-0336, United States.
authors.forename: Zongtang
authors.initials: Z
authors.lastname: Fang
authors.affiliation: Department of Chemistry, The University of Alabama , Shelby Hall, Box 870336, Tuscaloosa, Alabama 35487-0336, United States.
authors.forename: Johan
authors.initials: J
authors.lastname: Both
authors.affiliation: Department of Chemistry, The University of Alabama , Shelby Hall, Box 870336, Tuscaloosa, Alabama 35487-0336, United States.
authors.forename: Shenggang
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Chemistry, The University of Alabama , Shelby Hall, Box 870336, Tuscaloosa, Alabama 35487-0336, United States.
authors.forename: Shuwen
authors.initials: S
authors.lastname: Yue
authors.affiliation: William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Aprà
authors.affiliation: Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors.forename: Murat
authors.initials: M
authors.lastname: Keçeli
authors.affiliation: Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors.forename: Albert F
authors.initials: AF
authors.lastname: Wagner
authors.affiliation: Department of Chemistry, The University of Alabama , Shelby Hall, Box 870336, Tuscaloosa, Alabama 35487-0336, United States.
authors.forename: David A
authors.initials: DA
authors.lastname: Dixon