The energy required to generate a dislocation is proportional to the square of the
length of the Burgers vector, |b| . As a consequence, the most stable (lowest energy) dislocations have the minimum length |b|

a- For the BCC metal structure, calculate the dislocation energy for Eb={110} relative to Eb={111}
b- For the FCC metal structure, calculate the dislocation energy for Eb={111} relative to Eb={110}