Electron Distributions in Small Molecules

Mulliken's atomic gross charge and overlap populations are computed for the C3, C4, and C2N2 molecules. These populations are then compared with those of related molecules. The comparison is given in terms of s, p, and σ, π-atomic populations and σ, π-intramolecular charge transfer. The σ and π charge transfers are found to reinforce one another (one-way charge transfer) in homonuclear molecules and oppose one another (two-way charge transfer) in heteronuclear molecules. In addition, for the one-way case, the σ, π charge transfer is not as large as for the two-way case. It is pointed out that there are correlations between population analysis and orbital energies. This analysis of the electronic distribution is based on recent computations of simple and preliminary wave functions in the self-consistent field one-electron approximation.