Now, once again, according to Quantum Mechanics, if we begin with two atomic orbitals, we have to form two molecular orbitals. So far we've only seen one. Well, the second one is shown right up here, and it's called the phi antibonding molecular orbital. And we'll see why it's called antibonding in just a second. The first thing you have to notice about this antibody molecular orbital. If that is higher in energy than either of these guys, So let's move to this diagram here.