The performance of density functional theory for the description of ground and excited state properties of inorganic and organometallic uranium compounds

Emergence of the structure-directing role of f-orbital overlap-driven covalency

“…Building on our previous study of 2UBIPY 64 , we investigated a family of nine metalla-allene model systems [C] = M = E ([C] = C(PH 2 NSiH 3 ) 2 ; M = Ce IV , Th IV , U IV ; E = C(CH 3 ) 2 , NCH 3 , O), with a particular focus on the C-M-E angle, using the Gaussian-09 code 67 with two density functional approximations (DFAs). We used the generalised gradient approximation (GGA), PBE 68,69 , and related hybrid, PBE0 70 ; these DFAs are ideal as PBE has recently been shown to give accurate geometries in an extensive benchmarking study of organouranium systems 71 , and the GGA BP86 performs better than B3LYP and certain Minnesota functionals for some uranium bis carbene complexes 72 , and PBE0 is known to give improved energetics and has been previously applied by us to the study of a uranium(IV)-carbene-imido complexes 63,64 . Model complexes were sterically truncated and void of potassium ions and co-ligands to isolate electronic effects from steric constraints, and the final equilibrium geometries are obtained irrespective of whether the starting geometry is cis or trans with respect to the [C] = M = E angle.…”

Protactinium and the intersection of actinide and transition metal chemistry

“…All cluster geometries were optimized with the Turbomole package at the density functional theory level (DFT), using the PBE0 density functional with an ultrafine integration grid, m4, and converging the structure when the Cartesian norm reached 10 −4 atomic units 42 , 43 . The PBE0 functional was chosen as it gives accurate structural parameters for actinide species 44 . The minima were characterized by harmonic vibrational analysis.…”

DFT Investigations of the Magnetic Properties of Actinide Complexes

“…DFT-based calculations have also been reported [168] and proved to correctly reproduce chemical shifts of diamagnetic uranium(VI) compounds. DFT benchmarking calculations of 1 H and 13 C NMR chemical shifts of closed shell U(VI) systems for which experimental data are available (Figure 34), were reported [79]. Different levels of GGA and hybrid functionals were employed, i.e., B3LYP [86,87], PBE [148], PBE0 [149], LC-ωPBE [173,174], TPSS and TPSSh [175,176] and also including the Grimme's D3 dispersion corrections [150,157].…”

“…Therefore, these unique features of actinides relatively to transition metals and lanthanides open the way to the design of new actinide-based SMMs with high blocking temperatures [71,72,75]. Moreover, over the last twenty years, much effort has been devoted to investigating the magnetic properties of actinide complexes by quantum chemical methods [62][63][64][65]67,[70][71][72][73][74][75][76][79][80][81]. Indeed, investigating the electronic structure of actinide complexes is essential to understanding their magnetic behavior [1,2,[71][72][73].…”

“…However, for such a purpose, the use of a multiconfigurational post-Hartree-Fock approach is required, as stated by several authors [63,64,82,83], but such an approach is computationally demanding (vide infra) for polymetallic systems, notably for actinide ones, and usually simplified models are computed instead of the actual systems [63,64]. Thus, Density Functional Theory (DFT) appears as an alternative tool to compute magnetic exchange coupling and to explore the electronic structure and magnetic properties of actinide-containing molecules, especially when the considered systems are very large [6,8,21,37,60,79,80,84,85]. Indeed, DFT emerged in the early 2000s as a powerful technique, particularly when used in combination with the hybrid B3LYP functional [86,87] and the Broken-Symmetry (BS) Noodleman's approach [88,89], for satisfactory simulations of magnetic properties.…”