Rhombic preordering on a square substrate

TL;DR

This paper investigates how hard disks interact with a square substrate, revealing a rhombic preordering phase and reentrant transitions, using density functional theory and Monte Carlo simulations.

Contribution

It introduces the concept of rhombic preordering in a system with competing symmetries, combining theoretical and simulation methods to analyze phase behavior.

Findings

Identification of rhombic preordering structure

Reentrant square-rhombic transition with substrate interaction

Predictions applicable to colloid experiments in laser fields

Abstract

A competition of incommensurate symmetries occurs whenever a system is forced to conform to an ordering that is different from the intrinsically preferred structure of the system itself. As a model system of such a competition, we study the rivalry between the triangular ordering of hard disks and the square symmetry induced by a periodic square substrate. By using density functional theory as well as Monte Carlo computer simulations, we determine the full phase behavior for the case of one particle per minimum. We observe a rhombic preordering structure preceding the hexagonal solid as a direct consequence of the competing symmetries. Furthermore, the square-rhombic transition is reentrant with increasing substrate interaction. Our predictions can be verified in experiments of colloids in laser fields.