Even the 44 polyhedrons that resisted self-assembly could provide fodder for future designer materials. "Some of them we ran and ran [the simulation] and we just couldn't get them to form anything," Glotzer says. "But for every one of these particles that won't crystallize, there's another particle that looks almost the same that crystallizes every time." If researchers could figure out precisely what makes one particle assemble into a crystal whereas a near-twin languishes in a disordered state, they might be able to design shape-shifter particles whose collective properties would transform with a slight structural tweak to the individual building blocks.
"This is sort of a holy grail of materials research, to just look at a building block and be able to say, 'Oh yes, I know all of the kinds of crystal structure that would be stable with this,'" Glotzer says. "This study allows us to take a first step in that direction."