Understanding tetrahedral liquids through patchy colloids

Abstract

We investigate the structural properties of a simple model for tetrahedral patchy colloids in which the patch width and the patch range can be tuned independently. For wide bond angles, a fully bonded network can be generated by standard Monte Carlo or molecular dynamics simulations of the model, providing a neat method for generating defect-free random tetrahedral networks. This offers the possibility of focusing on the role of the patch angular width on the structure of the fully bonded network. The analysis of the fully bonded configurations as a function of the bonding angle shows how the bonding angle controls the system compressibility, the strength of the pre-peak in the structure factor and ring size distribution. Comparison with models of liquid water and silica allows us to find the best mapping between these continuous potentials and the colloidal one. Building on previous studies focused on the connection between angular range and crystallization, the mapping makes it possible to shed new light on the glass-forming ability of network-forming tetrahedral liquids.

Accurate phase diagram of tetravalent DNA nanostars

“…We also note that there is no evidence of a pre-peak, the typical signature of tetrahedral networks. It has been recently shown that there is a clear correlation between the strength (or the presence) of the pre-peak and the variance of the center-centercenter angle θ distribution [52]. For very wide θ distributions (as in the present case) the pre-peak is expected to be missing, since there is no sufficient geometrical correlation to establish a tetrahedral network.…”

Examples of Molecular Self‐Assembly at Surfaces

“…Such a minimal perspective is a com mon one in statistical mechanics, and many studies have shown that simple models can be used to describe a wide range of systems (see e.g., Refs. [19][20][21] for application to tetrahedral liquids). Correspondingly, several exam ples of molecular self-assembly at surfaces can be de scribed in common physical terms.…”

Connectivity, dynamics, and structure in a tetrahedral network liquid

“…Whereas at high temperatures (T = 0.14) the structure of the system is essentially that corresponding to a hard-sphere liquid with a main peak at qσ ∼ = 7, upon cooling the system we clearly see the signature of an archetypal tetrahedral structure by the emergence of an additional tetrahedral peak at qσ ∼ = 4.5. Thus, due to the judicious choice of the density and patch size, the system at low T exhibits no crystalline order but an amorphous tetrahedral network structurally similar to that present in atomistic systems such as silica or silicon [2,58], classical water models [42], or models of colloidal gels where double peak structures are imposed by means of three-body interactions [78].…”

“…Our particular realization consists of particles with four attractive patches tetrahedrally distributed on the particle surface [36,37]. Despite its simplicity, this and similar models [34,[38][39][40][41] have already shown the capability for capturing some of the fundamental structural features of different classical systems with amorphous tetrahedral structure such as atomistic models of water, silicon, or silica [2,[42][43][44]. In general, due to their highly versatile functionality, these models have not only the potential for promising applications [45][46][47] but they can also allow us to reach a deeper understanding of some of the intriguing phenomena manifested in gel and glassy systems [27,48].…”