All five of these Kekule and Dewar structures, considered individually, are wrong. There is no way to write the correct benzene structure as a set of single and double bonds, so the localized bond approximation, which has proven so useful for methane and other multi-atom molecules, breaks down. We must retreat a little way from localized bonds toward the whole-molecule approach again, at least where p electrons are concerned. We can combine the six p orbitals around the benzene ring according to the rules of MO theory, and produce the six full-ring MO's sketched above. In the lowest-energy orbital, all six p AO's are combined with the same sign to produce two rings of electron density above and below the plane of the benzene skeleton. There is zero electron probability in this plane because the original p orbitals had zero probability there. Like the two lobes of density in the p orbitals from which they came, the two "doughnuts" of probability in the , MO have opposite wave-function signs. The next most stable MO's, and , have the same energy and the same shape, with one horizontal or vertical plane of zero probability perpendicular to the benzene ring. Two antibonding orbitals with the same energy, and , each have two such zero-probability nodes at right angles, and the least stable antibonding orbital, , has three such nodes.