All-Electron Relativistic Fully Self-Consistent GW Study of Heteronuclear Actinide-Containing Diatomics.

The fully self-consistent GW (scGW) approximation provides a Green's-function approach that is starting-point independent and offers a favorable cost-to-accuracy balance compared to high-level wave function methods. Here, we present an all-electron scGW study of uranium-containing diatomics (UC, UN, UO, and UF), incorporating relativistic effects through the exact two-component (X2C) formalism. We evaluate adiabatic ionization energies as well as electron-attachment and detachment energetics (AEA and VDE), together with equilibrium structures and harmonic vibrational frequencies, and we assess their sensitivity to basis-set choice and relativistic treatment. We find that scGW yields ionization energies and vibrational properties in very good agreement with experiment and high-accuracy theoretical estimates. For AEA and VDE, diffuse basis sets are essential for convergence. UF is a particularly challenging case for scalar relativistic methods because its electron-attachment and vertical detachment energies are strongly affected by spin-orbit coupling, highlighting the importance of including SOC consistently in the electronic-structure treatment. These results establish all-electron X2C-scGW as a practical route for accurate actinide-molecule energetics and spectroscopy and motivate future applications to larger uranium-containing systems.