Population analysis and the effects of Gaussian basis set quality and quantum mechanical approach: main group through heavy element species

Abstract

Atomic charge and its distribution across molecules provide important insight into chemical behavior. Though there are many studies on various routes for the determination of atomic charge, there are few studies that examine the broader impact of basis set and quantum method used over many types of population analysis methods across the periodic table. Largely, such a study of population analysis has focused on main-group species. In this work, atomic charges were calculated using several population analysis methods including orbital-based methods (Mulliken, Löwdin, and Natural Population Analysis), volume-based methods (Atoms-in-Molecules (AIM) and Hirshfeld), and potential derived charges (CHELP, CHELPG, and Merz-Kollman). The impact of basis set and quantum mechanical method choices upon population analysis has been considered. The basis sets utilized include Pople (6-21G**, 6-31G**, 6-311G**) and Dunning (cc-pVnZ, aug-cc-pVnZ; n = D, T, Q, 5) basis sets for main group molecules. For the transition metal and heavy element species examined, relativistic forms of the correlation consistent basis sets were used. This is the first time the cc-pVnZ-DK3 and cc-pwCVnZ-DK3 basis sets have been examined with respect to their behavior across all levels of basis sets for atomic charges for an actinide. The quantum methods chosen include two density functional (PBE0 and B3LYP), Hartree-Fock, and second-order Møller-Plesset perturbation theory (MP2) approaches.

Similarities and Differences in Benzene Reduction with Ca, Sr, Yb and Sm: Strong Evidence for Tetra‐Anionic Benzene

“…QTAIM charges are based on the partitioning of electron density and present a low dependence on the basis set used in the calculation. [60] The geometry aligned perfectly with that of the crystal structure. The QTAIM charges for 3-Sm optimized in the + III OS are considerably higher (Sm: + 2.7, benzene: À 3.2) and underscore its different nature.…”

Similarities and Differences in Benzene Reduction with Ca, Sr, Yb and Sm: Strong Evidence for Tetra‐Anionic Benzene

“…By contrast, the QTAIM atomic partition provides partial charges very similar for the three complexes with high positive charges of +1.5 on Ca, Sr and Yb metal centres and −1.3 on the benzene ligand. QTAIM charges are based on the partitioning of electron density and present a low dependence on the basis set used in the calculation [60] . The geometry aligned perfectly with that of the crystal structure.…”

Investigating the interplay between charge transfer and CO2 insertion in the adsorption of a NiFe catalyst for CO2 electroreduction on a graphite support through DFT computational approaches

“…Therefore, the discrepancy between Orca and CP2K computed charges is mainly related to the method, and probably due to the basis set nature of CP2K computations 32 . The primary conclusion drawn from this comparison is that within the same method, the charges exhibit minimal change between the complex isolated or when adsorbed on the surface.…”