Integrated spatial electron populations in molecules: Application to simple molecules

The electron projection function P(x, z) = ∫ ρ(x, y, z) dy is used to evaluate charge transfer and covalency in two series of molecules, LiX and CH₃X (X = Li, BeH, BH₂, CH₃, NH₂, OH, and F), with wavefunctions derived from STO-3G, 4-31G, and, in some cases, 6-31* ab initio calculations. The precision of the method and comparison with Mulliken populations analysis are described. Particular attention is given to CH₃Li which by our criteria is wholly ionic.