Calculations of the spin susceptibility and the electronic thermal effective mass of Be and Mg by spin density functional theory

The spin-density functional theory was used to calculate the electronic thermal effective masses (including electron–electron interactions) and the spin susceptibilities (via a variational principle) for beryllium and magnesium. The necessary exchange-correlation functionals were treated in the local-spin-density approximation. The single-particle electron states were calculated by the augmented-plane-wave method using a self-consistent muffin-tin potential. It was found that the calculated thermal effective masses agreed very well with semi-empirical results from fits to the Fermi surface. We conclude that the accepted values of the electron–phonon mass enhancement parameter λep are too large by approximately 50%. The theoretical spin susceptibiltiy for Be was found to be 0.47 × 10−6 (cgs volume units), in marked disagreement with the experimental values. For Mg we obtained the value 1.65 × 10−6 (cgs volume units).