Electronic structure of alkaline earth metals, Ca and Be, as revealed by electron momentum spectroscopy (EMS)

Full text: For decades elements of the second group of the periodical table (alkaline earths) have been attracting attention of theorists and experimenters exploring the electronic structure of the solid state. Whereas the number of theoretical studies of their electronic structure is immense the experimental results reported in the literature are much more limited, especially for calcium. All physical and chemical properties of these elements mainly depend on their electronic structure. They have the closed-shell ns2 electronic configuration and owe their metallic behavior to the hybridization of s-p/d states. Electronic structure of bulk calcium is close to that of an ideal metal. As consequence its conduction-band dispersion resembles a characteristic free-electron-like parabola with a high density of states at the Fermi energy. On the other hand, beryllium presents distinctive features showing a large departure from free-electron behavior. Its electronic density of states is more like that of a covalently bonded semiconductor: it is low at the Fermi energy and the Fermi surface is not spherical. From the point of view of theoretical solid-state physics, Be metal plays the same role as He in theoretical atomic physics