This is lithium GAS. It is very sparse. They set up the conditions such that the “spin” of the Lithium ATOMS become progressively more uniformly aligned over time (very short times). You are right, they would tend to “clump” if they were able to be close enough to another Li atom (simply into a molecule Li2, in this case, to “fill the outer shell”). However, as the time goes by, the atoms instead repel each other due to the Pauli exclusion principle (they will repel more if they have same “spin”).
Aren’t Van der Waals (sp?) forces the reason that solids are solids? It’s more than just molecules, it’s molecules (or atoms) sticking to other molecules (or atoms).