Emergent tetratic order in crowded systems of rotationally asymmetric hard kite particles

Considering multi-body systems of monodisperse hard Brownian particles, it remains challenging to predict the forms of order that can emerge in their dense assembled structures. Surprisingly, here, using Monte Carlo simulations, we show that tetratic-ordered phases emerge in a dense two-dimensional system of hard kites that are rotationally asymmetric and have opposite 72 degrees and alpha approximate to 90 degrees internal angles. We observe a new tetragonal rectangular crystal (TRX) phase possessing (quasi-)long-range fourfold molecular-orientational order. We propose a method based on local polymorphic configurations of neighboring particle pairs (LPC-NPPs) to understand this emergent tetratic order and show that LPC-NPPs can be useful for predicting orientational order in such systems. To examine the dependence of the tetratic order on alpha, we apply LPC-NPP analysis to other hard kites for 54 degrees <= alpha <= 144 degrees. Our work provides insight into the creation of novel ordered materials by rationally designing particle shape based on anticipated LPC-NPPs. For colloidal particles, it remains challenging to predict the forms of order that can emerge in their dense assembled structures. Here, the authors show, by Monte Carlo simulations, that tetratic-ordered phases emerge in a dense two-dimensional system of hard kites that are rotationally asymmetric.