Landau theory and self-assembly of spherical nanoclusters and nanoparticles with octahedral symmetry

TL;DR

This paper develops a Landau theory-based phenomenological model to predict and analyze the self-assembly and structure of spherical nanoclusters and nanoparticles with octahedral symmetry, explaining known structures and predicting new complex forms.

Contribution

It introduces a novel method using irreducible octahedral density functions to predict structural arrangements in spherical nanoclusters with octahedral symmetry.

Findings

Explains structures of known metal nanoclusters and polyhedra.

Predicts complex chiral and achiral spherical structures.

Links octahedral functions to spherical lattice mappings.

Abstract

Spherical nanoclusters and nanoparticles are rising materials whose functional design provides many useful applications ranging from catalysis, molecular sensing, gas storage to drug targeting and delivery. Here, we develop phenomenological crystallization theory of such spherical structures with octahedral symmetries O and O_h. Within the developed theory, we propose a method, which is based on constructing irreducible octahedral density functions and allows to predict the positions of structural units in the spherical nanoobjects. The proposed theory explains the structures of the simplest known metal nanoclusters, some metal-organic polyhedra and membrane protein polyhedral nanoparticles, and also predicts more complex chiral spherical structures and achiral assemblies characterized by the geometry of semiregular polyhedra. A relationship between the constructed irreducible octahedral functions and spherical lattices, obtained by mapping a plane hexagonal order onto a spherical surface through an octahedron net, is discussed as well.