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: |^.^| what an idiot I am ... the solution is trivial!' +-!OO--\_/--OO!------------------------------+----------------------- ! Dr.Víctor Luaña ! ! Departamento de Química Física y Analítica ! ! Universidad de Oviedo, 33006-Oviedo, Spain ! ! e-mail: vic...@fluor.quimica.uniovi.es ! ! phone: +34-985-103491 fax: +34-985-103125 ! +----------------------------------------------+ GroupPage : http://azufre.quimica.uniovi.es/ (being reworked) _______________________________________________ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html