Re: How do you calculate the location of the third virtual image? Edit: I've made some progress on this one, and I now understand that the valence and conductance bands are composed of molecular orbitals contributed by each metallic atom joining the molecule. For example, three lithium atoms would contribute three total molecular orbitals, resulting in three bands. The bottom two might be the valence bands and hold all the elections, while the third might be the conductance band. Here's the question: Why does that third band (the conductance band) have a higher energy level than the valence bands, especially if they were all the same type of orbital (2s) contributed by lithium atoms?