User:Double sharp/Crystallographic properties of the elements

Data from Arblaster (2018), Selected Values of the Crystallographic Properties of Elements.

The data is for 293.15 K, unless we are dealing with elements that are not solid at that temperature (H, He, N, O, F, Ne, Cl, Ar, Br, Kr, Xe, Hg, Rn), when the triple point is used. No data is included for elements 104–118. There exists predicted data for some of those elements, but you will have increasing troubles as relativistic effects get higher, so the predictions are not in agreement. :)

For some reason only the triple point is given for Te and I. The data is for the usual 293.15 K still, as these are solid then.

For rhombohedral phases, both the rhombohedral parameters ar, α and the equivalent hexagonal parameters ah, ch are given. They are related by $$a_{h} = 2 a_{r} \sin (\alpha /2)$$, $$c_{h} = a_{r} \sqrt{3 + 6 \cos \alpha }$$, or (going the other way) by $$a_{r}^{2} = a_{h}^{2}/3 + c_{h}^{2}/9$$, $$ \sin ( \alpha /2) = a_{h} / (2 a_{r})$$. So really, you only need to give one set.