Electronic and structural properties of transition-metal carbide and nitride surfaces

The electronic structure and chemical bonding of the nitrides and carbides of Ti, V, Zr, and Nb are studied The augmented plane wave method is used and results are discussed in terms of energy bands and density of states (AIP)

Band structure and chemical bonding in transition metal carbides and nitrides

The phase stability of superstructures based on the fcc lattice in the Au-Pd and Ag-Pt alloy systems are examined from the fully relativistic electronic density functional theory. The electron-ion interaction is described by the projector augmented-wave PAW method and the exchange-correlation effects are treated in the generalized gradient approximation GGA. The cluster expansion method is used to obtain effective cluster interactions on the fcc lattice and is used also to guide a systematic ground state search for both alloy systems. The ground state analysis reveals a multitude of ground states in Au-Pd, especially at the Au-rich side. Possibly long-period super-structures occur near the Au70Pd30 composition. The ground state analysis indicates a uniquely stable AgPt compound with the L11 structure CuPt prototype and it also suggests a marginally stable ordered compound for Ag3Pt. However, our ab initio study rules out the existence of the remarkably stable Ag3Pt phase with L12 structure, reported first more than half a century ago and since then included in many assessments. We also find no indication for a stable ordered state at the AgPt3 composition. The cluster variation method CVM with a large maximal cluster is used to compute the enthalpy of mixing of the disordered solid solutions and the solid portion of the Au-Pd and Ag-Pt phase diagrams. These results are critically compared with experimental data and phase diagram assessments. It is shown that cluster expansions cannot account for the high-temperature miscibility gap in the Ag-Pt system when the effective cluster interactions do not reach beyond the second nearest neighbor. Only when third nearest neighbors are included in the cluster expansion is it possible to obtain a phase diagram that agrees qualitatively with the assessed Ag-Pt phase diagram.

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Ab initio calculation of the phase stability in Au-Pd and Ag-Pt alloys

Electronic states of monolayer graphite formed on TiC(111) surface

The electronic structure of SrTiO3 from a direct-transition analysis of angle-resolved photoemission data

Energy-band-structure study of the (100), (110), and (111) surfaces of TiC

Results of angle-resolved-photoemission measurements made on the (100) surface of a ${\mathrm{ZrN}}_{0.93}$ crystal are reported together with the results of a linear augmented-plane-wave band-structure calculation made for ${\mathrm{ZrN}}_{1.0}$. The calculated band structure is used to interpret the experimental data and a good agreement between calculated and experimental band locations and dispersions is obtained. A Tamm surface state is also identified on ZrN(100).

Energy-band-structure study of the ZrN(100) surface

Using the all-electron fully relativistic Karringa-Kohn-Rostoker coherent-potential-approximation method self-consistent total-energy calculations were performed for the system Au/Pd. The calculated equilibrium lattice constants are in fairly good agreement with the experimental data. In particular, microscopic reasons for the breaks in the variation of the lattice constants with concentration can be derived from the results. Since the calculations were carried out self-consistently for a maximum angular momentum quantum number of 2 as well as 3, an interesting quantitative comparison for the alloy total energies, spectral densities, and properties related to the Fermi energy or Fermi surface can be presented.

Calculation of equilibrium lattice parameters and the heat of mixing for the system Au/Pd by the relativistic Korringa-Kohn-Rostoker coherent-potential-approximation method.

J. Redinger

Papers

Energy-band-structure study of the (100), (110), and (111) surfaces of TiC

Energy-band-structure study of the ZrN(100) surface

Calculation of equilibrium lattice parameters and the heat of mixing for the system Au/Pd by the relativistic Korringa-Kohn-Rostoker coherent-potential-approximation method.