Characterization of gas phase WC²⁺: a thermodynamically stable carbide dication

Using an ab initio methodology, we performed a detailed theoretical study of the gas phase WC(2+) dication. These calculations were done using a multiconfigurational method in connection with a large basis set, where relativistic effects were taken into account. This dication is identified here as the first thermochemically stable doubly charged diatomic carbide in the gas phase. Our work hence confirms the stability of this dication in the gas phase and its earlier observations by atom probe mass spectrometry. Our calculations show that the shape of the potential energy curves of its lowest electronic states changes drastically upon consideration of relativistic effects. For instance, the electronic ground state possesses a Morse-like potential without spin-orbit that evolves to the usual volcanic behavior, and with a columbic 1/R evolution at large internuclear separation after inclusion of spin-orbit. We predict a set of thermochemical and spectroscopic data for this molecular species.