[Wien] structeditor

[Víctor Luaña Cabal]

On Fri, Nov 28, 2014 at 10:37:29AM +0000, Lawal Mohammed wrote:
> Dear Profs. Peter and Robert,
> Thank for your help.
> My doubt is clear now, but when you said..... 
> For FCC Cu, you have just ONE atom in the cell. I become comfused.
> I thought fcc Cu has FOUR atoms per unit cell i.e. corner atoms 8*1/8=1, and face centre atoms 6*1/2=3. 

Maybe you should try to read something of crystallography. The space
group of a fcc crystal is Fm-3m, and the Cu atom occupies the  (4a)
Wyckoff position (0,0,0) or the (4b) (1/2,1/2,1/2). That means that the
translation and rotation symmetry of the crystal provide no freedom to
the position of the atom. From a crystallographic perspective you have
4 atoms in the unit cell.

For a solid state physicists it is better to explore not the cubic
(crystallographic) cell but the primitive cell. In the primitive cell
you will have a single atom. If you want to observe the primitive cell
for the Fm-3m you can use the Bilbao crystallographic server, but for
this particular group there are many illustrations in solid state books.

Best regards,
             Dr. Víctor Luaña
--
       \|/a  "After years of working on a problem the genius shout:
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