Self-consistent calculation of electron density and muon hyperfine field in transition metals and their compounds

The use of finite cluster models to represent the electronic structure of solids in the framework of self-consistent local density theory is reviewed. The embedding problem is discussed, and practical variational approaches to treating crystalline potentials and wavefunction boundary conditions are presented. Hyperfine fields at ⁺ sites in Fe, Ni, and Co are found to result from a delicate balance between negative contributions of deep-lying (bound, paired) states and positive contributions due to polarization of band levels near the Fermi energy. The nature of muon screening, and the potential for ⁺ in Cu and Al are briefly considered. Finally, we explore the likely binding sites and bonding mechanisms for ⁺ in the defect compound VO _x .