Delocalization of Electrons in Molecules

We report a general method for the investigation and quantification of delocalization in molecules. The method is based on the anisotropy of the current-induced density (ACID). Compared to the current density, which has been frequently used to investigate delocalization, the ACID approach has several advantages: it is a scalar field which is invariant with respect to the relative orientation of the magnetic field and the molecule, it is not a simple function of the overall electron density, it has the same symmetry as the wave function, and it can be plotted as an isosurface. Several selected examples demonstrate the predictive power and the general applicability of this method.