Question on Molecular Orbital Theory (and the "dot" that represents no interaction) I have a question about the "dot" that represents no interaction between orbitals. For example, in the molecular orbitals of H3, there is the lowest energy molecular orbital that has two bonding interactions, the highest energy molecular orbital with two antibonding interactions, and a middle energy molecular orbital with no interaction (and a "dot" representing where the middle H orbital is). Why then, in say BeH2, does the molecular orbitals that have the "dot" not show up as one of the accepted molecular orbitals? The MO's of BeH2 I'm thinking of are the ones where you combine the 2s orbital of Be with the antibonding [itex]\phi[/itex] of H2. (and I guess the same question applies to when you combine the 2px of Be with the bonding [itex]\phi[/itex] of H2). Thanks for reading!