How does circular current emerge from linear systems? In α, ω-disubstituted even [n]cumulenes, the frontier orbitals are helical with alternating chirality. If the HOMO is a P-helix, the HOMO-1 is an M-helix, and the same principle applies to the virtual orbitals. Examples of helical MOs are shown in the right column of Figure and the middle column of Figure , and their origin has been explained in detail earlier. To highlight the circular component of the current density in 3, we change the coloring of the arrows of the current density. Instead of a Cartesian coordinate system where coloring is by the z-component, we change to a cylindrical coordinate system where coloring is by the ϕ-component.