Investigation of the compound Hf2Ni: the electronic structure and the electric field gradient

The electronic structure and electric field gradient (EFG) of the intermetallic compound Hf2Ni are calculated on the basis of a recently developed first-principles band-structure full-potential (FP) linear-muffin-tin-orbital (LMTO) scheme within the atomic sphere approximation (ASA). The calculated value of the EFG at the I-If sites is in very good agreement with the results obtained by the time-differential perturbed angular correlation (TDPAC) technique used for the experimental study of the EFG at Ta-181 impurity sites in the compound Hf2Ni. The asymmetry parameter eta and the individual contributions to the EFG are discussed. It is shown that various treatments of 4f hafnium electrons have a large influence on the EFG. The formulae for all of the components of the EFG tensor (the contributions from the valence electrons as well as the lattice contribution) are derived and presented also