Abstract
The authors introduce a new model for the screened Coulomb potential appropriate to dilute interstitial hydrogen impurities in a metallic host. This new potential provides an accurate representation of the self-consistent potential of a proton in an electron gas and is more suitable than the customary Thomas-Fermi potential in that it yields a charge density which is finite at the impurity site. Calculations have been performed using this new potential and the screened Coulomb potential employed in earlier work, for the case of hydrogen in palladium. Neither the change in the electronic structure, Delta N(E), nor the change in the total energy, Delta E, are found to be very dependent on the exact form of the screened Coulomb potential. The theoretical formalism has also been extended to the case of dilute hydrogen interstitial impurities in the FCC transition metals Ni and Rh. In both metals Delta E is found to be approximately -1.1 Ryd, and the octahedral site is predicted to have lower energy in agreement with experiment.