 | Acta Crystallographica Section A Acta Crystallographica Section A FOUNDATIONS AND ADVANCES |
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![[Figure 9]](ae5132fig9mag.jpg)
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Figure 9
A chiral spiral cyclic twin with m = 7 and μ = 1. Shown are 7 × 52 = 364 nodes (mostly represented by blue discs of unit diameter). The spiral branch at k = 0 is highlighted with respect to its alternating all-trans configured segments (orange discs) and its pattern-breaking cis-configured corners (red discs), conferring curvature to the spiral branch. Overlaid are three out of seven equally spaced half-involute spirals originating from a base circle of radius RI (red circle and spirals at k = 0, 1, 2) forming a double orthogonal system with three out of seven equally spaced half-lines (green lines). The spiral branch at k = 1 shows a rectified curve (orange polygonal curve or spirangle) used for the estimation of a spiral branch's arc length in relation to that of its corresponding circle involute. Note that RI does not yield a perfectly symmetric separation of the twin boundaries (green lines), for which a slightly smaller radius RB proves to be better suited (cyan lines). A third radius RC is associated with the perfect delineation of the twin centres (magenta lines). |
![[Figure 9]](ae5132fig9.jpg)
| FOUNDATIONS ADVANCES |
ISSN: 2053-2733
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