A comparative study of DFT and traditional ab initio methodologies on the OsO4 molecule

The performance of different conventional ab initio methodologies and densi ty functional procedures is compared through its application to the theoret ical calculation of the bond distance and harmonic vibrational frequencies of the OsO4 molecule. The problem of the basis set is first considered, wit h up to nine different basis sets being tested in calculations using the hy brid Becke3LYP density functional, and the most appropriate basis set is us ed in the comparison of Hartree-Fock, post-Hartree-Fock, and density functi onal methods. The post-Hartree-Fock methods analyzed are MP2, CISD, and CCS D(T), and the density functionals tested are SVWN, BLYP, BPW91, and Becke3L YP. The results show that for this particular system density functional met hods perform better than do HF-based methods with the exception of CCSD(T), which gives the best overall results. (C) 2000 John Wiley & Sons, inc.