Density Functional Theory Study of the Gas-Phase Reaction of U⁺ with CO₂

The gas-phase reaction of U⁺ with CO₂ was investigated with B3LYP density functional theory (DFT) in conjunction with the relativistic effective core potential (ECP) of the SDD basis sets for Uand the 6-311 + G(d) basis set for C and O. The potential energy surfaces (PESs) of the reaction system were explored in detail for both doublet and quartet spin states. The geometries of reactants, intermediates, transition states, and products in the two reaction pathways were fully optimized. The reaction mechanism was analyzed using"two-state reactivity (TSR)."The calculations demonstrate that the reaction preferentially involves the high-spin state entrance channel and the low-spin state exit channel. The spin multiplicity transition from the quartet state to the doublet state enables the reaction system to find a lower energy pathway.