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