Favoured local structures in liquids and solids: a 3D lattice model

Abstract

We investigate the connection between the geometry of Favoured Local Structures (FLS) in liquids and the associated liquid and solid properties. We introduce a lattice spin model – the FLS model on a face-centered cubic lattice – where this geometry can be arbitrarily chosen among a discrete set of 115 possible FLS. We find crystalline groundstates for all choices of a single FLS. Sampling all possible FLS's, we identify the following trends: (i) low symmetry FLS's produce larger crystal unit cells but not necessarily higher energy groundstates, (ii) chiral FLS's exhibit peculiarly poor packing properties, (iii) accumulation of FLS's in supercooled liquids is linked to large crystal unit cells, and (iv) low symmetry FLS's tend to find metastable structures on cooling.