Electronic structure and superconductivity of Europium
We have calculated the electronic structure of Eu for the bcc, hcp, and fcc crystal structures for volumes near equilibrium up to a calculated 90 GPa pressure using the augmented-plane wave method in the local-density approximation. The frozen-core approximation was used with a semi-empirical shift of the f-states energies in the radial Schr$\ddot{o}$dinger equation to move the occupied 4f valence states below the $Γ_1$ energy and into the core. This shift of the highly localized f-states yields the correct europium phase ordering with lattice parameters and bulk moduli in good agreement with experimental data. The calculated superconductivity properties under pressure for the $\it bcc$ and $\it hcp$ structures are also found to agree with and follow a $T_c$ trend similar to recent measurement by Debessai et al.$^1$