Stability of the decagonal quasicrystal in the Lennard-Jones-Gauss system

TL;DR

This study investigates the stability and transformation mechanisms of a decagonal quasicrystal in a Lennard-Jones-Gauss system, revealing its entropic stabilization and the energetics of its approximants.

Contribution

It demonstrates that the decagonal quasicrystal is entropically stabilized and identifies the approximant Xi as having the lowest potential energy in the system.

Findings

Decagonal phase is an entropically stabilized random tiling.

Approximant Xi has the lowest potential energy.

Quasicrystal transforms into approximant Xi below a critical temperature.

Abstract

Although quasicrystals have been studied for 25 years, there are many open questions concerning their stability: What is the role of phason fluctuations? Do quasicrystals transform into periodic crystals at low temperature? If yes, by what mechanisms? We address these questions here for a simple two-dimensional model system, a monatomic decagonal quasicrystal, which is stabilized by the Lennard-Jones-Gauss potential in thermodynamic equilibrium. It is known to transform to the approximant Xi, when cooled below a critical temperature. We show that the decagonal phase is an entropically stabilized random tiling. By determining the average particle energy for a series of approximants, it is found that the approximant Xi is the one with lowest potential energy.