Resonating valence bonds: A new kind of insulator?

The possibility of a new kind of electronic state is pointed out, corresponding roughly to Pauling's idea of “resonating valence bonds” in metals. As observed by Pauling, a pure state of this type would be insulating; it would represent an alternative state to the Néel antiferromagnetic state for S = 1/2. An estimate of its energy is made in one case.