Universal Kernel

crystal

The three-dimensional net of tallies, Sunada’s K4K_4 crystal, which the program reads as space.

(0; 0,0,0)12(0; 1,0,0)12(0; 2,0,0)3one period(1, −1, −1)
Plate W.17The triangle 0→1→2→00\to1\to2\to0 lifted to the crystal: each step rises a third of a period and turns by 120∘120^\circ, and after three steps the walker is at a site of type 0 again, one period (1,−1,−1)(1,-1,-1) higher.

As mathematics

The maximal abelian cover X=T/[F3,F3]X=T/[F_3,F_3] of K4K_4, with deck group H1(K4;Z)≅Z3H_1(K_4;\Z)\cong\Z^3, in its standard realization: each oriented letter is projected onto the circulation space by P=I−14∂T∂P=I-\tfrac14\partial^{\mathsf T}\partial. Every edge has squared length 12\tfrac12, the three edges at a site meet at 120∘120^\circ in a plane, and the periods are the integer triples with coordinates of equal parity. Sunada showed that among three-dimensional crystal nets with injective standard realization the strongly isotropic ones are the diamond and the K4K_4 crystal, the latter with its mirror image.

It has girth 10. Its decagons fall into six classes and include the cyclic reductions of the commutators of the triangle loops, and on the tori X/nZ3X/n\Z^3, n=4,5n=4,5, they span the cycle space. The dilation by bb about a vertex maps vertices to vertices exactly when b≡0b\equiv0 or 1(mod4)1\pmod4, since the vertex classes are points of order 4 in the Jacobian (Z/4)2(\Z/4)^2 of K4K_4.

Its name in another fieldBridge
Sunada’s K4K_4 crystalbuilt
the srs netbuilt
the Laves graphbuilt
Wells’s (10,3)(10,3)-abuilt
the hyperoctagon lattice of Kitaev modelsclassical
spacea reading
Builds
arena