Population analysis, charges, configurations

The four secular equations H- — WG [ = 0 are solved as follows For a given cycle, an input electron configuration and charge are assumed for the metal, and the terms are computed. terms for ligand basis functions remain constant throughout the calculation. For each of the MO s calculated in the cycle, a Mulliken population analysis is performed, in which each overlap population is divided equally between the two basis functions involved.<16)... 

Each VSIE is a function (empirically established) of charge and electronic configuration the latter is obtained by Mulliken s population analysis ° conducted on the molecular orbitals. Therefore an iterative method is required. Each secular determinant is solved in cycles until self-consistent charge distribution is obtained. Some relation between the output from one iteration and the input from the next is often necessary to ensure convergence... 

Atomic charge, orbital energy, and population are important pieces of information for determining electronic configuration, net charge association, and the nature of the bond. Mulliken population analysis is a widely used method in most ab initio molecular orbital calculations. However, reports about Mulliken population analysis that fail to yield reliable characterization of molecular systems have appeared. A more accurate method for population analysis, NBO, was... 

In semiempirical MO-LCAO calculations of any type, for instance the iterative extended Huckel (lEH) type , the charges on atoms, and more specifically their electronic configurations, are usually calculated by means of a Mulliken population analysis. (Other population analyses may also be efficient). For instance, for the p-electron density on atom A we have ... 

The NAO populations, as tabulated in 1/0-3.1, make it easy to sum up the total number of electrons in each ( ,/) subshell to obtain the natural electron configuration. Similarly, the total electronic population on the atom can be combined with the nuclear charge to obtain the net namral charge for each atom, and other aspects of the electronic bookkeeping can be summarized for informational purposes. Such summaries follow the table of detailed NAO orbital occupancies (1/0-3.1) in the natural population analysis (NPA) section of NBO output. 

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