Strain field and electric field gradient for interstitial point defect in simple metals

The strain field and electric field gradient for interstitial proton in simple fee metals are investigated. The proton occupies octahedral site in fee metals. The defect induced charge density used to evaluate valence effect electric field gradient (q^v) is calculated self-consistently in the non linear density functional approach using the spherical solid model potential for discrete lattice and Blatt correction for lattice dilation. The elastic continuum model is used to evaluate size effect electric field gradient (q^s) considering the dressed point ions interacting through screened Coulomb potential. Both q^v and q^s are found cylindricaly symmetric at both the first and second nearest neighbours (NNs) yielding the asymmetry parameter (η) to be zero. q^s is found dominating over q^v by an order of magnitude. The phase shifts are found converging and the scattering is more prominent in Al than in Cu. Both the valence and strain fields are equally important to explain the electric Field gradient (EFG).