Molecular geometry, charge distribution and polarization in platinum nitrides. An ab initio and density functional theory study of PtNN, PtPtNN, NPtPtN, and NNPtNN

摘要

We have calculated molecular geometries, atomic charges, dipole moments and polarizabilities for the linear platinum nitrides PtNN, PtPtNN, PtNNPt and NNPtNN. The calculation of the electric properties relies on finite-field M011er-Plesset perturbation theory and Coupled Cluster techniques. Our best values for the polar PtNN and PtPtNN molecules are calculated at the CCSD(T) level of theory and are μ/ea_0 = -0.7089 (PtNN) and -0.1196 (PtPtNN), α/e~2 a_0~2E_h~(-1) = 56.60 (PtNN) and 123.06 (PtPtNN), Δα/e~2a_0~2E_h~(-1) = 27.40 (PtNN) and 68.18 (PtPtNN). For PtNNPt and NNPtNN we obtain α/e~2a_0~2E_h~(-1) = 120.51 (PtNN) and 79.02 (PtPtNN), Δα/e~2a_0~2E_h~(-1) = 116.38 (PtNN) and 76.75 (PtPtNN). Compared to the best values, the performance of the DFT methods is rather erratic.