Magnetically Induced Current-Density Susceptibility of Circum[n]coronenes.

We have calculated the magnetically induced current density (MICD) susceptibility at the all-electron density functional theory level for a series of coronoid molecules of increasing size and compared the MICD susceptibilities with those calculated using the pseudo-π (PP) model. The molecules sustain global diatropic magnetically induced ring currents (MIRCs), whereas paratropic MICD vortices mainly appear inside the benzene rings. The computationally cheaper PP calculations were also employed on circum[n]coronene molecules showing that the MICD pattern continues to alternate for odd and even n when increasing the size of the molecule. For even n, there is a local paratropic MIRC in the middle of the molecule, whereas when n is odd, the PP models do not sustain any paratropic MIRC pathways. The global diatropic MIRC flowing mainly along the outer edge of the molecule increases with increasing n suggesting that there is no size limit of the MIRC of circum[n]coronene molecules. There are seven weakly aromatic Clar rings in the middle of the PP model of the circum[n]coronene molecules with odd n, whereas circum[n]coronene molecules with even n have no Clar rings. There are no Clar rings in the outer part of the circum[n]coronene molecules with n > 1.