Crystals … diamond structure, and something called K_4

I am going to have to look up the article referred to by /. This morning, they linked to an article in AMS about crystal symmetry, and a structure they called K_4. This structure, they claimed, does not occur in nature.
Odd I thought … as the picture they showed, well, I thought I had seen it before.

So using Inventor, I pulled out an old copy of a Gallium Arsenide lattice I used for simulations, more than a decade ago (aren’t open formats nice?) and put it up on the screen, right next to the structure that doesn’t exist in nature.This is what I saw

K_4 versus GaAs lattice

Not seen in nature? You be the judge.
As noted, I need to read the article, it is possible that their picture is mislabeled, and they are showing a diamond lattice where they mean to be showing a different lattice.
That said, lattices are extremely well studied.

2 thoughts on “Crystals … diamond structure, and something called K_4”

  1. BTW: the picture on the right is the Gallium Arsenide lattice I used to use for molecular dynamics simulations many (eek!) years ago. I had created VRML (and Open Inventor) files out of the chemistry coordinate files something like 12 years ago. The ivview is a program that renders these Open Inventor scene-graphs to screen, and allows you to interact with them, rotate them, fly through them … light them differently, and so on.

  2. When I first read about it on slashdot my first guess before I read the article was that he’d probably rediscovered hexagonal diamond or something similar.
    However it is a different structure.
    The perspective makes it difficult to see though.
    Start at the central atom and go straight up until you hit the first bunch of atoms. There are three distinct fractional coordinates in the atoms there.
    The reason it’s not seen in nature is because chemically speaking it’s an awful structure.
    There are several different bond lengths which in an elemental lattice will introduce lots of strain. It will spontaneously convert into another lattice.
    Someone will probably put it through a modelling package and do the sums and verify this.
    If he’d tried to publish this in a structural chemistry journal then I have a feeling it would have been shot down in flames.

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