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Electronic structure of nonstoichiometric cubic hydrides

Description: Using the supercell approach we have calculated the electronic structure of Y/sub 4/H/sub 8/, Y/sub 4/H/sub 9/, Y/sub 4/H/sub 11/, and Y/sub 4/H/sub 12/ as prototypic of nonstoichiometric cubic di- and trihydrides. The nature of the interaction between the yttrium and the octahedral and tetrahedral hydrogens is shown by the relative amount of charge contained in the crystal spheres. Each added hydrogen lowers one band which was already partially filled. The charge on both the octahedral and tetrahedral sites is very similar and significantly more than is contained in a comparable atomic sphere.
Date: January 1, 1980
Creator: Switendick, A.C.
Partner: UNT Libraries Government Documents Department

Electronic states in the vanadium--ruthenium system

Description: We have calculated the energy bands of ordered vanadium-ruthenium alloys having the observed cesium chloride and tetragonal distortion thereof which occurs near 50-50 composition. Those calculations were performed self-consistently and using two sets of exchange parameters. The Fermi energy was found to fall near maxima and minima of the energy bands consistent with a large density of states and the observed large electronic specific heat and superconducting transition temperature. In particular with increasing ruthenium concentration the Fermi energy rises and intersects (in a rigid band sense) the doubly degenerate states X5 creating two electron Fermi surfaces. Under the tetragonal distortion those states are perturbed and split becoming lowered in the (100) and (010) directions and raised in the (001) directions. This causes a decrease in the density of states at the Fermi energy and modification of the Fermi surface. These states are associated with vanadium d-character as was inferred from susceptibility and NMR measurements. The band structure provides a qualitative model for understanding this system.
Date: January 1, 1977
Creator: Switendick, A. C.
Partner: UNT Libraries Government Documents Department

Theoretical studies of hydrogen in metals: current status and further prospects

Description: Electronic band structure studies of metal-hydrogen systems have demonstrated the existence of large metal-hydrogen and hydrogen-hydrogen interactions. These interactions lead to the formation of stable hydride phases. Factors governing this interaction are investigated for various different structures. Possible new directions for theoretical research are indicated.
Date: April 1, 1978
Creator: Switendick, A.C.
Partner: UNT Libraries Government Documents Department

Bandstructure calculations for metal hydrogen systems

Description: The factors contributing to hydride stability are discussed for a variety of metal hydride systems. The formation of a low-lying hydrogen associated state is a common feature. A significant transition metal character is also found in these states.
Date: January 1, 1979
Creator: Switendick, A.C.
Partner: UNT Libraries Government Documents Department

Electronic structure and charge density of zirconium diboride

Description: Self-consistent calculations of the electronic band structure of zirconium diboride, ZrB{sub 2}, have been performed. The total and individual band charge densities are analysed in terms of their site (zirconium or boron) symmetry and plotted. The total charge density shows very little charge asymmetry about either site. 6 refs., 6 figs., 37 tabs.
Date: January 1, 1990
Creator: Switendick, A.C.
Partner: UNT Libraries Government Documents Department