(53j) Digital Alchemy for the Inverse Design of Patchy Particles

Patchy particles are an exciting development for the fields of colloidal and nanomaterials. The ability to tailor interparticle interactions offers the promise of precise control of the self-assembly of patchy particles into structures with desirable properties. Given the many possible “degrees of anisotropy,” the design space of patchy particles is enormous, prohibiting the direct exploration of this space and making inverse design methods a crucial tool for the field. Of the many inverse design methods developed to date, digital alchemy is particularly attractive for patchy particles. Digital alchemy is an extended ensemble method that incorporates particle properties into the thermodynamic ensemble, allowing inverse design via statistical-mechanically-rigorous, on-the-fly updates to interparticle pair potentials. In this work, we extend the digital alchemy framework for the inverse design of patchy particles, and design triblock Janus particles to self-assemble target crystal structures. We provide examples of symmetric triblock Janus particles in 2- and 3-dimensions that self-assemble the open kagome and pyrochlore lattices, respectively. To highlight the generality of our method, we also present the inverse design of asymmetric triblock Janus particles to self-assemble a snub square lattice, whose coordination has a lower symmetry than the kagome and pyrochlore lattices, and therefore requires patches of differing sizes. Surprisingly, particles designed based upon geometric considerations are unable to self-assemble into the snub square lattice, whereas particles designed via our digital alchemy framework do, highlighting the ability of the method to find nontrivial solutions to the design problem. This work shows how digital alchemy can be used to design arbitrary patchy interactions to self-assemble into desired crystal structures, and can be built upon to design patchy particles of arbitrary shape and patch configuration.