Augmented Plane Wave Study of Electric Field Gradients in Non-cubic Metals

Abstract

Abstract The electric field gradient (EFG) in body-centered tetragonal Indium metal and hexagonal closed packed Beryllium metal is calculated on the basis of a full potential scalar relativistic augmented plane wave procedure. The various contributions to the EFG in simple metals are discussed. The total EFG in In metal found theoretically is equal to qtheor = 2.67 x 1021 Vm-2 . This value agrees well with the experimental data. Using the quadrupole moment Q deduced from the hyperfine splitting of the muon X-ray spectra one gets g exp = 2.46 x 1021 Vm-2 . The valence electrons of Indium give a direct contribution of qel = 2.72 x 1021 Vm-2 , whereas the direct ionic contribution q ion is much smaller and has opposite sign: qion = -0.01 x 1021 Vm-2 . There is a small net shielding contribution of qsh = -0.03 x 1021 Vm-2 to the EFG composed of the ionic contribution gsh. ion = -0.39 x 1021 Vm- 2 and the valence electron contribution qsh,ve = 0.36 x 10 21 Vm-2 .