Compact Polyhedra of Cubic Symmetry: Geometrical Analysis and Classification

TL;DR

This paper provides a detailed geometrical analysis and classification of compact polyhedra with cubic symmetry, introducing parameters that describe their shape and size, with applications to nanoparticle shape estimation.

Contribution

It introduces a systematic classification scheme for compact polyhedra of cubic symmetry using a minimal set of parameters, expanding understanding of their geometrical properties.

Findings

Polyhedra are characterized by three or four structure parameters.

Shape, size, and surface facets are analytically described.

Relationships enable shape classification and size estimation of nanoparticles.

Abstract

Compact polyhedra of cubic point symmetry Oh, exhibit surfaces of planar sections (facets) characterized by normal vector families {abc} with up to 48 members each, compatible with Oh symmetry. We focus first on polyhedra confined by facets with normal vectors of one family, {100}, {110}, and {111}, separately. This yields generic polyhedra which serve for the definition of general compact polyhedra as intersections of the three generic species. Their structural properties, such as shape, size, volume, and surface facets, are found to be described by only three polyhedral structure parameters A, B, C. In addition, we examine compact polyhedra exhibiting facets defined by normal vectors of only one general {abc} family resulting in up to 48 facets. These polyhedra can be described by four polyhedral structure parameters Q, a, b, c. Geometrical properties of all polyhedra are discussed in analytical detail and substantiated by visualization of characteristic examples. Corresponding relationships can also be used to classify shapes and estimate sizes of real compact metal nanoparticles observed e.g. in electron microscopy experiments.