Thursday, March 26, 2015

Torus knot (2,9) by Kazunori Horibe

Kazunori email these photos of a beautiful bead model of (2,9)-Carbon nanotube torus knot (CNTTK) he just made the other day. To make the structure more clearly, I also use the Grapher to create the corresponding torus knot.

Wednesday, March 11, 2015

Hyperbolic soccerball

I posted many hyperbolic bead models before. But most of them are periodic surface structures in 1- to 3-D dimensional spaces. Examples are various periodic minimal surfaces. In these models, one needs to pay attention to the subtle periodic conditions in the course of beading. Sometimes, it makes the beading quite difficult.
Here, I show a simple construction of hyperbolic soccerball (truncated order-7 triangular tiling) consisting of infinitely many heptagons (blue beads), each of them are connected to seven neighboring heptagons by only one carbon-carbon bond, which is represented by a yellow bead in the model shown below.
Following the spiral beading path by adding hexagons and heptagons, eventually one obtains the hyperbolic soccerball, or more exactly a hyperbolic graphitic snowflake. There is no need to worry about the periodic conditions among different parts of the structure.
From wiki: Truncated order-7 triangular tiling
In principle, one can also use kirigami (paper cutting) to make a model of the hyperbolic soccerball. But I found that the beading technique is much easier for making robust structure of this object due to the nature of mathematical beading. Also the bead hyperbolic soccerball should be able to model the local force field of hyperbolic soccerball to certain extent because the bead model not just gives the connectivity of the molecular graph right, but also mimics the microscopic repulsions among chemical bonds.

Thursday, November 13, 2014

Ping-Pong Valence Sphere Model

Valence sphere models, a qualitative chemical bond model that includes the influence of the electron pair repulsion among valence electron pairs and attraction between positive atomic core and negative electron pairs, can be constructed with Ping-Pong balls easily. Here, I made three pairs of linked ping-pong balls and used them to create a tetrahedral sp3-hybridized AX4 system and a octahedral d2sp3 hybridized AX6 system.

Wednesday, November 12, 2014

Beautiful photo of Chern's C60@60 at the Columbia Secondary School

The superbuckyball, C60@C60, made by Chern is now on exhibition at the Columbia Secondary School, New York. This is for an event called MoSAIC—Mathematics of Science, Art, Industry, Culture—the festival, an offshoot of the annual Bridges Organization international conference dedicated to the connections between art and mathematics.

There is a nice photo of this C60@C60 in the Columbia Spectator.

Thursday, November 6, 2014

Bead model of Klein's all-heptagon network

I took a picture of single tetrahedral unit (12 heptagons) of D56 bead model on the figure depicting schematically an open network consisting only of heptagons, described by Klein in his 1879 paper.

Klein, F. (1878). "Ueber die Transformation siebenter Ordnung der elliptischen Functionen" [On the order-seven transformation of elliptic functions]. Mathematische Annalen 14 (3): 428–471. Translated in Levy, Silvio, ed. (1999). The Eightfold Way. Cambridge University Press.

C20 vs C56