What I have read is that the contents of the unit cell affect
the intensities, but how? I am also unclear on why you need to
know the symmetry of the unit cell, what is that used for? I
understand segments of this topic (x-ray crystallography) but I
am having trouble piecing all the segments together to make a
complete picture. I've been spending hours every day on this on
this, any help would be really appreciated! Two questions here:
1) What does the symmetry of the crystal mean? The symmetry of
the unit cell is the symmetry of the crystal. Its really useful
thing to know about the crystal in practice. You can always
pretend that any crystal is space group P1 - with no internal
symmetry. This implies half of the diffraction data is needed to
get a complete set. Why half? The Laue symmetry of typical X-ray
diffraction shows that the diffraction should be centrosymmetric
I(hkl) = I(-h,-k,-l). If you do this and the crystal has more
symmetry than that you are collecting too many data. Here I take
the example o