For α<0, the minimum for the energy is at θ = π/2, meaning that the orientation is perpendicular to the z-axis and lying on the xy-plane.

For α=0, the energy expression turns to 0 for all values of θ, meaning that the energy is independent of the orientation with respect to the z-axis.

For α>0, the minimum for the energy is at θ = 0 and π, meaning that the orientation is parallel to the z-axis.