Electric-Field Gradient at Cu Nuclei Due to an Interstitial Positive Muon

The electric-field gradient caused by an intersitital positive muon at near-neighbor Cu nuclei is calculated from first principles. The electron density distribution around the ${\mu }^{+}$ is obtained using the self-consistent density-functional formalism and the Bloch enhancement factor is computed from a band-structure model based on the tight-binding scheme. Good agreement with recent experimental result is obtained.