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[en] A new approach, based upon augmented-plane-wave calculations in a supercell lattice, was developed to theoretically predict the annihilation characteristics of the positron in vacancies, taking into account for the first time the atomic nature of the solid. This method, which is general and suited equally well to both simple and transition metals, was used to calculate positron trapping and annihilation characteristics in Al, Nb, Ta, and W. The results indicate that the positron is sufficiently strongly trapped in a vacancy in all of these metals that significant thermal detrapping in any of them is highly unlikely. 13 references

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[en] Many situations arise in pulsed power devices in which there has to be a transition made from strip line to coaxial-line

[en] The generalized magnetic susceptibility (q) of Sc metal has been determined from accurate augmented plane wave (APW) method calculations of their energy band structure using a novel computational scheme developed as an extension of the work of Lehmann and Taut and Jepsen and Andersen on the density-of-states problem. The procedure yields simple analytic expressions for the (q) integral inside a tetrahedral microzone of the Brillouin zone which depends only on the volume of the tetrahedron and the differences of the energies only at its corners. Constant matrix element results have been obtained for Sc which show very good agreement with the results of Liu, Gupta and Sinha

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[en] The occurrence of superconductivity in the metallic phase of hydrogen is re-examined. While the band structure is quite free electron-like, the wavefunctions look like atomic wavefunctions near the protons. A consideration of the electron-phonon interaction reveals that the motion of the bound part of the electron wave-functions considerably decreases the effective electron-phonon coupling constant over previous estimates. The alternative derivation of the electron-phonon coupling constant in terms of phase shifts is also discussed and the effects of screening are considered. Again the estimates of T/sub c/ are found to be considerably reduced by screening effects

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[en] In this paper we review the theoretical and experimental data concerning point defects and diffusion in metallic glasses. We shall show that even though simulations seem to indicate that point defects could exist under certain conditions in glassy alloys there is not yet clear experimental evidence for their existence; in addition their role in atomic transport is not clear since the diffusion mechanisms are not known todate. To conclude, we propose specific experiments and simulations which could be helpful for a better understanding of these phenomena