Fig. 3 ACID isosurfaces of the model complex 2′ separated into the π- and σ-contribution. ACID isosurfaces of the model complex 2′ separated into the π- and σ-contribution. Current-density vectors are plotted onto the ACID isosurface of 0.035. (A and B) The diatropic ring current displayed in the periphery of the 6MR and the fused 5MRs indicates the π-aromaticity (A), whereas the diatropic ring current only exists in the 3MR, indicating the σ-aromaticity (B). The magnetic field vector is orthogonal with respect to the ring plane and points upward (clockwise currents are diatropic). Congqing Zhu et al. Sci Adv 2016;2:e1601031 Copyright © 2016, The Authors