Problem $1$

Draw $2$D Patterson map $($on the ab plane$)$ of the set of atoms in the cubic unit cell having coordinates: $(0,0,0),(0\mathrm{.}4,0,0),(0\mathrm{.}2,0\mathrm{.}2(3),0)($see the figure below$).$

b

a

Reminder: Patterson map as a self$-$convolution of the density map will contain all points pointed $($from $(0,0,0)$ by vectors joining any two atoms.