Validation of self-consistent hybrid approaches for the study of transition metal complexes. NiCO and CuCO as case studies

The structures, binding energies and harmonic force fields of NiCO and CuCO have been studied using extended basis sets with the recent B3LYP self-consistent hybrid method. Introduction of some Hartree-Fock exchange delivers a significant improvement over current density functionals, approaching the accuracy of the most refined post Hartree-Fock computations. CuCO has a bent equilibrium structure with a sizeable barrier to linearity (15 kJ mol−1), whereas NiCO is linear. After correction for the basis set superposition errors, the binding energy of both species is in good agreement with experimental estimates.