Application of various population methods to some oxygenated compounds

Abstract

The charge on oxygen for a series of compounds was obtained using Mulliken population, natural population analysis (NPA), integrated projected electron population (IPP) analysis, and Bader's topological density analysis, "integrated Bader populations" (IBP). The orbital-based methods (Mulliken and NPA) predict oxygen charges of about -0.6 whereas the spatial-based methods (IPP and IBP) predict charges of about -1.2 to -1.3. The differences are ascribed primarily to the nuclear-centered basis sets used in the orbital methods that minimize local atomic polarization effects. Accordingly, such population analyses should be used for electronic structure considerations only with due circumspection. The IPP method as an approximation to IBP shows gross similarities; small but significant differences vary in a nonsystematic manner and IPP values must also be used with care.

AIM and NPA Studies of the Role of Polarization in Electronic Structures

“…The AIM charges in Table differ substantially from those given by NPA. In part, this comes from a size effect in the AIM treatment, a property of AIM criticized by Perrin and discussed by us and others, that results in a charge on oxygen much greater for AIM than NPA. But, in part, the difference results from hydrogen being effectively more electronegative than carbon in AIM but less electronegative in NPA.…”

High-Level Computational Studies of Nonidentity Proton Transfer Reactions: Variations in Their Gas Phase Potential Energy Surfaces

“…They provide rigorously defined, physically meaningful measures of the charges on each of the atoms. Previous work has shown that this approach is far superior to conventional Mulliken population analysis . The ρ value is the density at the critical point of a bond where the critical point is defined as the density minimum along the bond path connecting the two atoms.…”

PRODEN: A new program for calculating integrated projected populations

“…( 2 , -2)p, (2,0)p, and (2,2)p, can be identified.' These correspond to local maxima, saddle points and local minima on the density surface, and occur at the atomic positions, the internuclear regions and the centers of cyclic compounds, respectively?…”

“…The new program implements two entirely different partitioning techniques, one based on the analytically evaluated gradient field of the two-dimensional function, and the other on a local approximation inferred from a rectangular grid of points. In addition to the electron projection function, PRQDEN can calculate averaged slab densities, R(x, z), defined as the average of p(x, y, z ) in an interval b centered at some point a along a given Cartesian axis (2) planar densities, D ( x , z ) , i.e., cross-sections of p(x, y, z), evaluated at some fixed point a along a given axis…”