A quantitative measure of bond polarity from the electron localization function and the theory of atoms in molecules

A quantitative measure of the polarity of a bond can be obtained through co mbining the two complementary topological partitionings of the electron den sity obtained from the atoms in molecules theory, on the one hand, and the electron localization function, on the other. This requires an integration of the electron density in the atomic subbasins of a common bond electron l ocalization basin. We present the first numerical application of the result ing topological definition of bond polarity to a set of small linear system s consisting of the FCN, HF, HCl, HBr, and NaCl molecules and the NeAr van der Waals dimer. It is shown that the findings are essentially in line with common expectation for these simple molecules, thus confirming the potenti al value of the novel bond polarity index for the analysis of controversial bonding situations. Additional insight is provided through the detailed in vestigation of fluctuations in the basin populations.