papers [113, 114] via near Hartree-Fock representations of magnetic-field induced
current density field. No proof for strong diatropism was found for the cyclopropane
molecule in a magnetic field normal to the carbon plane.
The essential features of J
B are understood by the SG shown in Fig. 7.23 and by the
current density maps of Fig. 7.24. The SG is very different from that of p-aromatic C n H n
cyclic system analyzed in Sect. 7.5.2. It shows that the primary vortical SL branches out
into four vortical and three saddle SLs. Two far-off (0, 0) critical points, not visible in
the figure, lie on the C 3 axis, at a distance of more than 10 bohr from the centre of mass.
The Gomes theorem, Eq. (7.59), is fulfilled: three diamagnetic vortical SLs, each lying
on a Tr v symmetry plane, pass through the C nuclei, then they bend outward at some
Fig. 7.23 Perspective view
of the stagnation graph of the
current density vector field in
cyclopropane. The uniform
external magnetic field,
B B 3 , is parallel to the z
axis. Green (red) lines denote
diamagnetic (paramagnetic)
vortices, saddle lines are blue
198
P. Lazzeretti