Photodetachment spectra of the PtX42- (X=F,Cl,Br) dianions and their Jahn-Teller distortions: A fully relativistic study

In this work we calculate the photoelectron spectra of the PtX(4)(2-) (X=F,Cl,Br) dianions by application of the third-order Dirac-Hartree-Fock one-particle propagator technique. Relativistic effects and electron correlation are hereby treated on a consistent theoretical basis, which is mandatory for systems containing heavy elements. An experimental PtF(4)(2-) gas phase photoelectron (PE) spectrum is not available and our calculations confirm its instability against autodetachment. For PtCl(4)(2-) potential curves for the two Jahn-Teller (JT), active modes were determined and the influence of spin-orbit splitting on the JT stabilization is discussed. The scalar relativistic and four-component potential energy curves hereby exhibit remarkable differences relevant for the correct interpretation of the spectra. A dissociation channel through the b(2g) vibrational mode was obtained for PtCl(4)(2-) in the (2)E(u) final state. For all species electron correlation strongly decreases the ionization potentials and the inclusion of spin-orbit coupling leads to alterations in the level order, which have to be taken into account for a correct peak assignment. The metal d contribution to the valence orbitals steadily decreases from the PtF(4)(2-) to the PtBr(4)(2-) compound, which rules out a pure metal d-orbital-based interpretation of the valence PE spectrum.