Relativistic effects at the Cu₂O₂ core – a density functional theory study

Abstract

This work presents for the first time the impact of relativistic effects on the CuO peroxide dicopper(ii)-bis(μ-oxo) dicopper (iii) equilibrium bonding motif in existing tyrosinase model complexes [Cu(btmgp)(μ-O)] and [Cu{HC(tBuPz)Py}(O)] [S. Herres et al., Inorg. Chim. Acta, 2005, 358, 1089; S. Herres-Pawlis et al., Eur. J. Inorg. Chem., 2005, 3815; A. Hoffmann et al., Angew. Chem., Int. Ed., 2013, 52, 5398]. We use density functional theory (TPSSh/cc-pVTZ+D3BJ) with various relativistic approaches (ECPs, DKH, ZORA) to tackle the question of impact and find, as already known for small model complexes in the literature, that the O core is more stabilized with respect to the P core by the relativistic influence [D. G. Liakos and F. Neese, J. Chem. Theory Comput., 2011, 7, 1511]. Whereas DKH and ZORA yield similar results, ECPs underestimate the predicted effect. By calculating the functional of the relativistic overlap change, we can exactly identify the relativistic changes at the molecular orbital level and narrow down the affected MOs. Thus, by performing a detailed bond analysis utilizing the overlap population, we are able to rationalize the effects at the chemical level by finding relativistic bond stabilization in both isomers, which is more dominating in the O core. In conclusion, relativistic effects already play an important role in dicopper cores and should be considered.

Utilizing the Surface Electrostatic Potential to Predict the Interactions of Pt and Ni Nanoparticles with Lewis Acids and Bases—σ-Lumps and σ-Holes Govern the Catalytic Activities

“…Furthermore, the use of ECPs is an inexpensive way of accounting for relativistic effects since the fixed core potentials have been optimized to include relativistic effects. 37 It has been found that the scalar relativistic effects in ECPs can give similar results as the relativistic allelectron calculations when analyzing ground-state (MSPA) properties. 23 All starting geometries and multiplicities of the bare nanoparticles were adopted from Chaves et al 38 and were obtained with the all-electron full-potential Fritz Haber institute ab initio molecular simulations (FHI-aims) package 39,40 using the PBE functional and the tight_tier1 basis set for geometry optimization.…”

“…In addition, the hybrid meta-GGA functional TPSSh and a triple-zeta basis set with polarization functions have shown better performance in the optimization of ground-state structures and provide improved results for energies of transition-metal complexes of various spin and oxidation states compared to other evaluated functionals. , The Def2-TZVP comprises effective core potentials (ECPs) for 4d and 5d metals and provides a good balance between accuracy and computational cost. Furthermore, the use of ECPs is an inexpensive way of accounting for relativistic effects since the fixed core potentials have been optimized to include relativistic effects . It has been found that the scalar relativistic effects in ECPs can give similar results as the relativistic all-electron calculations when analyzing ground-state (MSPA) properties …”

Automatic Construction of the Initial Orbitals for Efficient Generalized Valence Bond Calculations of Large Systems

“…However, several low-lying isomers may coexist, depending on the ligands coordinated to two copper atoms. Previous studies have demonstrated that the electronic structures of these systems have strong multireference characters, and the evaluation of the relative energies among different isomeric species is quite challenging for many theoretical methods. ,,− Here we are interested in the relative energy between two isomers of a di-copper–oxygen–ammonia complex, labeled as bis and per , as shown in Figure . The relative energies of these two isomers have been investigated by many theoretical methods. , Here we will first investigate whether the use of the initial GVB orbitals constructed with our procedure can lead to the converged GVB energies for two isomers.…”

“…The Cartesian cc-pVTZ basis set is employed for Cu and O atoms and cc-pVDZ for N and H atoms. Relativistic effects are not considered, although there is indication that they may play an important role in these two species. , …”

“…Relativistic effects are not considered, although there is indication that they may play an important role in these two species. 113,114 For the studied compounds, the UHF solution is more stable than the RHF solution, so scheme II was used. Two UHF solutions exist for these species; the lowest UHF solution was employed for constructing the initial GVB orbitals.…”