𝑘 / corresponds to the Boltzmann constant and 𝜃 0 to the Debye temperature, which is 400 K for magnesium. The surface energy 𝛾 is defined as the surface excess free energy per unit area and was calculated by subtracting a multiple of the bulk energy 𝑁 • 𝐸 '()* from the energy of the slab 𝐸 1)$' , divided by the area of the surface 𝐴 times two (because of the symmetric slab configuration):