In the following models, the sp2 carbon atoms are dark gray and the hydrogens are cyan. The different phases of the molecular orbitals are colored red and blue and are separated by nodal surfaces at which electron density is zero. π-orbitals are formed by overlap of p-orbitals having like phases. The lowest energy π-orbital, has a single nodal plane, that of the atoms. The higher energy π-orbital has two nodes, the second perpendicular to the first. The molecules can be rotated by clicking on the structure and dragging the mouse. Holding the shift key during this operation allows zooming.