Homogeneous Ni catalysts for H2 oxidation and production: an assessment of theoretical methods, from density functional theory to post Hartree-Fock correlated wave-function theory.

摘要: A systematic assessment of theoretical methods applicable to the accurate characterization catalytic cycles homogeneous catalysts for H(2) oxidation and evolution is reported. The key elementary steps involve heterolytic cleavage H-H bond formation/cleavage Ni-H N-H bonds. In context density functional theory (DFT), we investigated use functionals in generalized gradient approximation (GGA) as well hybrid functionals. We compared results with wave-function theories based on perturbation (MP2 MP4) coupled-cluster expansions [CCD, CCSD, CCSD(T)]. Our findings indicate that DFT Perdew correlation are semiquantitative agreement CCSD(T) results, deviations only a few kilocalories/mole. On other hand, B3LYP not even qualitative CCSD(T). Surprisingly, MP2 found be extremely poor, particular diproton Ni(0) dihydride Ni(IV) species reaction potential energy surface. Hartree-Fock reference wave function gives poor state description these states electron rich Ni, giving rise erroneous energies. present detailed potential-energy diagram by after accounting effects solvation, modeled polarizable continuum, free estimated at harmonic level theory.