Talk:Diamond cubic

message: The article describes the positions of atoms in a unit cell as follows:
 Atomic placement in unit cell of side length a is given by the following placement vectors.
 \mathbf{r}_0 = \vec{0}
 \mathbf{r}_1 = (a/4)(\hat{x} + \hat{y} + \hat{z})
 \mathbf{r}_2 = (a/4)(2\hat{x} + 2\hat{y})
 \mathbf{r}_3 = (a/4)(3\hat{x} + 3\hat{y} + \hat{z})
 \mathbf{r}_4 = (a/4)(2\hat{x} + 2\hat{z})
 \mathbf{r}_5 = (a/4)(2\hat{y} + 2\hat{z})
 \mathbf{r}_6 = (a/4)(3\hat{x} + \hat{y} + 3\hat{z})
 \mathbf{r}_7 = (a/4)(\hat{x} + 3\hat{y} + 3\hat{z})
No explanation is given for what the \hat{x}, \hat{y}, or \hat{z} mean.
Just in case they represent standard unit basis vectors, wouldn't it be a lot clearer if the article presented the coordinates of the atoms in a unit cell of side length = 1, without inventing mysterious symbols for the unit basis vectors?  Also, they could be ordered in an organized manner. The list of points would then be as follows:
(  0,   0,   0),
(1/4, 1/4, 1/4),
(1/2, 1/2,   0),
(1/2,   0, 1/2),
(  0, 1/2, 1/2),
(3/4, 3/4, 1/4),
(3/4, 1/4, 3/4),
(1/4, 3/4, 3/4).
Daqu (talk) 06:23, 2 April 2008 (UTC)
thread_title: Greater clarity

message: In the first paragraph, it says that "silicon/germanium alloys in any proportion" follow the diamond structure. That's not accurate. The overall positions of atoms may be the same as in the diamond structure, but if the atoms are not all the same, the structure is different. For example, with a 50-50 ratio, the material could be the zinc-blende structure. Diamond and zinc-blende do not share the same space group, as this article would imply.  — Preceding unsigned comment added by Johncolton (talk • contribs) 00:11, 31 December 2010 (UTC)
thread_title:  Incorrect information 

message: I think the rotating figures would be much more useful if the rotation could be stopped at any frame by clicking. (Even more useful might be if they could be rotated by the user, but that is secondary.)  — Preceding unsigned comment added by 71.191.142.176 (talk) 14:19, 6 August 2016 (UTC)
replies: text: I agree. Having two nearly identical rotating figures is just plain stupid. The article NEEDS a drawing of the unit cell. Not something that moves around in random directions. It took me several minutes to even count the number of atoms in the videos: ridiculous!!!98.21.210.4 (talk) 15:25, 10 June 2017 (UTC)
thread_title:  Rotating figures 

message: *As the diamond structure looks like a polycyclic cage-type hydrocarbon taken to extremes, can it be said that a diamond crystal is a single giant covalent molecule? Anthony Appleyard (talk) 22:45, 6 August 2017 (UTC)
replies: text: There is nothing in the definition of a molecule that rules out network solids, but people who study these solids don't tend to call them molecules. It seems there is nothing to be gained or lost either way, so go nuts. Student298 (talk) 21:19, 9 August 2020 (UTC)
thread_title:  Giant molecule 

message: This page gives the following list of points for locations in a single lattice unit, scaled up to a side length of 4:
(0,0,0), (0,2,2), (2,0,2), (2,2,0), (3,3,3), (3,1,1), (1,3,1), (1,1,3)
However, the exploded lattice diagram shows a lattice unit comprising eight sub-units, where four of these sub-units are empty and the other four consist of a tetrahedron with a captured point in the center. That corresponds to a point list of:
(0,0,0), (0,2,2), (2,0,2), (2,2,0), (1,1,1), (1,3,3), (3,1,3), (3,3,1)
The first four points could be thought of as the four corners of the tetrahedron anchored at the origin, or alternately the anchor points of the four non-vacant sub-units; the last four points correspond to the captured point within each sub-unit tetrahedron, each offset by (1,1,1) from its anchor point.
The points as listed, however—along with the equation that produces them—require the "captured" points to be at the centers of the VACANT sub-units, rather than at the centers of the tetrahedrons.
Which of these is correct?
Cirne (talk) 14:10, 2 May 2022 (UTC)
replies: text: The diagrams are not labeled by their coordinate axes. Isn't it just a question of relabeling? —David Eppstein (talk) 15:56, 2 May 2022 (UTC)
thread_title:  "Mathematical Structure" section does not match diagrams