Compact Polyhedra of Cubic Symmetry: Geometrical Analysis and Classification

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.