In this section we will look at the Patterson function of a more
Use to open a second copy of the applet in a new window.
For this exercise there are two copies of the Structure Factor
applet - the second is in a new window or tab. This one shows the Patterson
resulting from the five marked atoms, and the other shows the electron
Examine the Patterson carefully, and work out which interatomic
vectors correspond to each Patterson peak. There are two peaks (and
their opposites) which are higher than the others: one to the right
of the origin, and one up and right from that (in fact they are
precisely twice as high). Looking at the interatomic vectors, can you
work out why?
As the number of atoms increases, the Patterson becomes much more
complex and difficult to interpret. Once symmetry is introduced,
duplicated vectors become common. Vectors between an atom and one of
its symmetry equivalents, known as Harker vectors, can be helpful in
trying to interpret the Patterson. These peaks may usually be
identified becuase they lie in special sections of the Patterson.