Now we can see the dislocation has formed. We can think of the dislocation as a moving origin from which we can estimate the displacements, and thus the energy. Changing α alters the position of the dislocation in relation to the unit cell. α is the fraction of the unit cell across which the dislocation has moved.

At α = 0.25, this is the maximum misfit energy that must be overcome for the dislocation to move through the cell. The corresponding stress is the Peierls stress.

At α = 0.5, we are at an energy minimum. the extra half plane of atoms has moved by 1/2 a unit cell. But the atoms themselves have only moved by max b/6.

At α = 0.75, this is the maximum misfit energy that must be overcome for the dislocation to move through the cell. The corresponding stress is the Peierls stress.

At α = 1, the extra half plane of atoms has moved by 1/2 a unit cell. But the atoms themselves have only moved by max b/3.

At α = - 0.25, this is the maximum energy that must be overcome for the dislocation to move through the cell. The corresponding stress is the Peierls stress.

At α = -0.5, we are at an energy minimum. the extra half plane of atoms has moved by 1/2 a unit cell. But the atoms themselves have only moved by max b/6.

At α = -0.75, this is the maximum misfit energy that must be overcome for the dislocation to move through the cell. The corresponding stress is the Peierls stress.

At α = -1, the extra half plane of atoms has moved by 1/2 a unit cell. But the atoms themselves have only moved by max b/3.

Here we have two crystal lattices of the same material.