Energy band structure of Ca, Sr and Ba

Abstract

Attempts have been made to apply the `quantum defect method', in conjunction with the `composite wave variational method', to compute the band structure of divalent metals calcium, strontium and barium. The quantum defect data have been deduced from experimental spectroscopic eigenvalues of singly-ionized Ca, Sr and Ba. The presence of an extra electron in each atomic cell has been taken into account by assuming a uniform charge density which produces a potential -2Z/r - Zr²/r³_s, r_s being the radius of the Wigner-Seitz cell and Z being the valency of the metal. The calculation of the band has been performed for all these metals neglecting - Zr²/r³_s. Then an attempt has been made to take into account the term - Zr²/r³_s in the case of Ca. Both these calculations show that the Fermi surface of Ca is dismembered around the symmetry point W inside the Brillouin zone.