Configuration population analysis

It is essential to have high-quality data in place for interoperable systems to function efficiently. Standard data structures can only be used to full advantage if they are combined with standard terminology for values populating a data element. Yet there are many potential pitfalls in data collection and configuration for analysis. Some of the more common pitfalls are discussed here, but this list is by no means comprehensive. 

The quality of the ) states has been tested through their energy and also their transition moment. Moreover from the natural orbitals and Mulliken populations analysis, we have determined the predominant electronic configuration of each ) state and its Rydberg character. Such an analysis is particularly interesting since it explains the contribution of each ) to the calculation of the static or dynamic polarizability it allows a better understanding in the case of the CO molecule the difficulty of the calculation and the wide range of published values for the parallel component while the computation of the perpendicular component is easier. In effect in the case of CO ... 

Natural population analysis of transition-metal-fluoride wavefunctions gives orbital populations that are generally consistent with the expected configurations, but with large departures from an idealized ionic picture. Table 2.4 compares the... 

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)... 

There have been a few VB calculations on this molecule, particularly since the recent advances in computer capability make the problem of non-orthogonality of the orbitals less serious. Maclagan and Schnuelle384 have reported the results of a minimal-basis STO calculation, including all configurations which do not involve excitation of the Be core electrons. Comparison with a MO calculation was made. A VB equivalent to the CNDO/2 method was proposed. Gallup et a/.385 have also carried out a similar calculation and proposed a population analysis scheme for VB wavefunctions. Other calculations on BeKfe by these workers have appeared.116-118... 

One rather satisfactory way is to introduce all valence electrons in the molecular orbital approach without a hypothesis on the hybridization of atomic orbitals. Population analysis using the CNDO/2-SCF-MO showed the electronic configuration of the nitrogen atom of aromatic nitrogen cation systems (1, 40, 41, 42, 43, 44) in the ground state to be as follows (69G1078) ... 

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... 

As is done with the basis, the embedding may be improved by generating external atomic densities for atoms with the configurations that they have in the cluster, as obtained by the Mulliken population analysis ... 

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