Programmable self-assembly of diamond polymorphs from chromatic patchy particles

We present a method of controlling polymorphism in self-assembly and apply it to the long-standing problem of assembly of a colloidal diamond. The latter is often viewed as the ``holy grail'' of the self-assembly field, due to the challenge that it presents as well as thanks to its potential as a step towards manufacturing of photonic band-gap materials. In our approach, we use a ``chromatic'' version of traditional building blocks, the so-called patchy particle. Namely, the individual patches that belong to the same particle in our model are distinguishable (``colored'') and their pairwise interactions are color dependent, which could be implemented with the help of DNA fictionalization. We propose a design procedure and verify it with the help of Brownian dynamics simulations. Not only are we able to ``program'' the self-assembly of a high-quality cubic diamond lattice, but a small modification of the coloring scheme also allows us to ``reprogram'' the system to assemble into the alternative polymorph, a hexagonal diamond.