Ground and excited states of PtCH2+: assessment of the no-pair Douglas–Kroll ab initio model potential method
Relativistic all-electron and ab initio model potential (AIMP) calculations have been performed on the PtCH2+ ground and low-lying excited states employing a one-component Hamiltonian. Electron correlation is taken into account by means of a multireference configuration interaction treatment whereas spin–orbit coupling effects have been added as a perturbation. The no-pair Douglas–Kroll ab initio model potential method is found to reproduce all-electron results excellently. The one-center spin–orbit mean-field Douglas–Kroll ab initio model potential approach appears to be a competitive means for electronic structure calculations on compounds containing heavy elements. An analysis of the PtCH2+ electronic ground state structure reveals that both the Pt+ configurations d9 and d8s1 participate in the double bond. This finding differs to some extent from a model postulating that a d8s1 structure is preferred.