Ground-state configurations of decagonal and dodecagonal binary dipolar quasicrystals

Abstract

We search for ground states of binary decagonal dipolar quasicrystals increasing the parameter space step by step: first testing tiling types and small-scale approximants, then allowing continuous deformation of the tiles, and finally by simulated annealing through tile flips followed by local optimization. It turns out that the quasicrystals are not a true ground state but can be favoured in finite systems by the lack of costly defects. Similar studies for square-triangle binary dipolar quasicrystals show that there the energy reduces with the number of square pairs. Phase-separated crystals turn out to be more stable then quasicrystals.

Keywords:

• approximants
• colloids
• computer simulation
• crystal structure
• quasicrystals

Acknowledgement

The author was supported by the Collaborative Research Center 716 of the German Research Foundation DFG. Thanks to F. Scheffler for providing Figure 1.