Interactive Tutorial about Diffraction
Structure solving: Part II

Structure solution
Tasks part 1
Answers part 1
Tasks part 2
Answers part 2
Tasks part 3
Answers part 3


Lets summarize the knowledge we have so far from our earlier work:

  Lattice constants:                 5,5,5, 90, 90, 90
  Chemical Formula:                  Zr Ti O4
  Number of molecules per unit cell: 1
  Plane group:                       pmm4 

With this information we can calculate the Patterson for both experimental intensities according to the previous formula. The resulting Pattersons are shown in the images below. The left image shows the X-ray Patterson, the right image the neutron Patterson. Note that both functions are periodic function in real space. Again clicking on the images will give you a full screen picture.

Again there is some homework to do, before going to the next chapter.

  • Why is the Patterson density a periodic function in real space ?
  • Explain the differences between the X-ray and neutron Patterson
  • Why are the neutron Patterson peaks at 1/2 1/2 0 and at 0.2 0 0 negative ?
  • Solve the structure, at least for the metal atoms.
© Th. Proffen and R.B. Neder, 2003