Cluster self-assembly condition for arbitrary interaction potentials

We present a sufficient criterion for the emergence of cluster phases in an ensemble of interacting classical particles with repulsive two-body interactions. Through a zero-temperature analysis in the low density region we determine the relevant characteristics of the interaction potential that make the energy of a two-particle cluster-crystal become smaller than that of a simple triangular lattice in two dimensions. The method leads to a mathematical condition for the emergence of cluster crystals in terms of the sum of Fourier components of a regularized interaction potential, which can be in principle applied to any arbitrary shape of interactions. We apply the formalism to several examples of bounded and unbounded potentials with and without cluster-forming ability. In all cases, the emergence of self-assembled cluster crystals is well captured by the presented analytic criterion and verified with known results from molecular dynamics simulations at vanishingly temperatures. Our work generalises known results for bounded potentials to repulsive potentials of arbitrary shape.

Automated summary

The study presents a criterion for determining the emergence of cluster phases in a collection of classical particles with repulsive two-body interactions. By analyzing at zero temperature in the low density region, the relevant characteristics of the interaction potential that lead to the energy of a two-particle cluster-crystal becoming smaller than a simple triangular lattice are identified. The method is applied to various examples of potentials with and without cluster-forming ability, and the emergence of self-assembled cluster crystals is well captured by the presented analytic criterion.