Fang Fang, Richard Clawson, Klee Irwin (2018)
In geometrically frustrated clusters of polyhedra, gaps between faces can be closed without distorting the polyhedra by the long established method of discrete curvature, which consists of curving the space into a fourth dimension, resulting in a dihedral angle at the joint between polyhedra in 4D. An alternative method—the twist method—has been recently suggested for a particular case, whereby the gaps are closed by twisting the cluster in 3D, resulting in an angular offset of the faces at the joint between adjacent polyhedral. In this paper, we show the general applicability of the twist method, for local clusters, and present the surprising result that both the required angle of the twist transformation and the consequent angle at the joint are the same, respectively, as the angle of bending to 4D in the discrete curvature and its resulting dihedral angle. The twist is therefore not only isomorphic, but isogonic (in terms of the rotation angles) to discrete curvature. Our results apply to local clusters, but in the discussion we offer some justification for the conjecture that the isomorphism between twist and discrete curvature can be extended globally. Furthermore, we present examples for tetrahedral clusters with three-, four-, and fivefold symmetry.
Article
Closing Gaps in Geometrically Frustrated Symmetric
Clusters: Local Equivalence between Discrete
Curvature and Twist Transformations
Fang Fang 1,*, Richard Clawson 1,2 and Klee Irwin 1
1 Quantum Gravity Research, Topanga, CA 90290, USA; richard@QuantumGravityResearch.org (R.C.);
klee@QuantumGravityResearch.org (K.I.)
2
Faculty of Health, Engineering and Sciences, University of Southern Queensland,
Toowoomba, QLD 4350, Australia
* Correspondence: Fang@QuantumGravityResearch.org
Received: 24 April 2018; Accepted: 23 May 2018; Published: 25 May 2018
Abstract: In geometrically frustrated clusters of polyhedra, gaps between faces can be closed
without distorting the polyhedra by the long established method of discrete curvature, which
consists of curving the space into a fourth dimension, resulting in a dihedral angle at the joint
between polyhedra in 4D. An alternative method—the twist method—has been recently suggested
for a particular case, whereby the gaps are closed by twisting the cluster in 3D, resulting in an angular
offset of the faces at the joint between adjacent polyhedral. In this paper, we show the general
applicability of the twist method, for local clusters, and present the surprising result that both
the required angle of the twist transformation and the consequent angle at the joint are the same,
respectively, as the angle of bending to 4D in the discrete curvature and its resulting dihedral angle.
The twist is therefore not only isomorphic, but isogonic (in terms of the rotation angles) to discrete
curvature. Our results apply to local clusters, but in the discussion we offer some justification for
the conjecture that the isomorphism between twist and discrete curvature can be extended globally.
Furthermore, we present examples for tetrahedral clusters with three-, four-, and fivefold symmetry.
Keywords: quasicrystals; geometric frustration; space packing; tetrahedral packing; discrete
curvature; twist transformation
PACS: 61.44.Br
MSC: 52C17; 52C23; 05B40
1. Introduction
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