Invoking a DFT + U approach, we explored self-interaction artifacts in results from Kohn-Sham (KS) density functional calculations on the geometry and the vibrational frequencies of uranyl monohydroxide and the corresponding tetra-aqua complex. Exchange-correlation functionals based on the local density approximation (LDA) and the generalized-gradient approximation (GGA) predict equilibrium geometries for [UO2(OH)](+) that deviate from the results of hybrid DFT calculations and high-level wavefunction-based methods such as CCSD(T). LDA + U and GGA + U functionals with corrections for the insufficient localization of the U 5f shell yield better agreement, in particular for the angle U-O-h-H. At the LDA level, a linear coordination of the OH ligand results; with the +U correction, the angle U-O-h-H is reduced by similar to 35A degrees, in good agreement with CCSD(T) results. At the GGA level, the bending angle is changed by similar to 20A degrees. This relatively strong self-interaction artifact is traced back to a spurious pi interaction between U 5f and O(p) orbitals which is less pronounced in the presence of further (aqua) ligands.
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Invoking a DFT + U approach, we explored self-interaction artifacts in results from Kohn-Sham (KS) density functional calculations on the geometry and the vibrational frequencies of uranyl monohydroxide and the corresponding tetra-aqua complex. Exchange-correlation functionals based on the local density approximation (LDA) and the generalized-gradient approximation (GGA) predict equilibrium geometries for [UO2(OH)](+) that deviate from the results of hybrid DFT calculations and high-level wavefu...
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