Recent content by johannes919

Thanks!

So, I get that there are two atoms in the primitive cell of the Diamond lattice, while there's only one in the fcc lattice. But do we get optical modes if the two atoms are identical? Referring to your answer in Wminus' post, it would seem to me that as the atoms in the primitive cell are...

Ah, ok. So the reason is that the primitive unit cell of the fcc lattice only consists of one atom, while the primitive unit cell of diamond consists of two?

Aluminium has an fcc structure, which is a simple cubic lattice with four Al-atoms in the basis. On the other hand, diamond has a diamond structure, which is a simple cubic lattice with 8 atoms in basis. Now, diamond has optical modes in addition to acoustical, while Aluminium does not. What...