Can electron delocalization be revealed through the Source Function?

The Source Function (SF) [1,2] enables one to view chemical bonding and other chemical paradigms under a new perspective and using only information from the electron density observable, rho, and its derivatives. Being completely independent from the tools used to get rho, the SF represents a very useful descriptor, able in many cases to bridge the gap between the rich information ine gains from an ab-initio wavefunction of an ideal system and that, quite often more limited, but referred to a real system, obtained from an experimental rho derived from X-ray diffraction data. The potential uses of SF are, however, not fully explored. In this lecture we discuss our recent work where the question of wheter the SF is or not capable to reveal electron delocalization has been addressed [3,4]. [1] R. F. W. Bader, C. Gatti, Chem. Phys. Lett. 1998, 287, 233-238. [2] C. Gatti, C. Cargnoni et al., J. Comput. Chem. 2003, 24, 422-436. [3] C. Gatti, Struct. Bond. 2011, 1, DOI: 10.1007/430_2010_31 [4] E. Monza, C. Gatti, L. Lo Presti, E. Ortoleva, J. Phys. Chem. Article ASAP DOI: 10.1021/jp204000d, Richard Bader's Festchrifte issue