Interpretation of crystallographic groups under Riemann's elliptic geometry

Abstract

This paper is devoted to the problem of choosing the most suitable model of a geometrical system for describing the real crystallographic space. It has been shown that all 230 crystallographic groups used to describe the crystalline structures in a Euclidean space can be presented by elliptic motions in the closed space $V^3$. Based on these results, it is stated that a special geometric system---the crystallographic space of interpretation $R_E$, determined by a form of an interpretant (the surface of a torus $T^2$ can serve as this interpretant)---can serve as a geometrical model of the real crystallographic space. The compact model of the closed structure of a crystal has been proposed and ways of its treatment for visualizing the constructions of elements of symmetry of a crystalline lattice in the Euclidean space $E^3$ have been determined. As a modeling space for describing the internal structure of a crystal, the closed space $V^3$ with the elliptic metrics and constant positive Gaussian curvature ($K=1$) has been offered. The properties of the internal space of a real crystal are naturally deduced from the properties of the modeling space.