General Nonlocal Theory Research Articles

Structure and dynamics of a two-component metallic glass

The structure of a two-component metallic glass (Mg70Zn30) is described by a relaxed model structure of 800 atoms. The authors use realistic pair potentials calculated from general nonlocal pseudopotential theory, and periodic boundary conditions. The cluster has been given the shape of a regular rhombic dodecahedron, the most sphere-like space filling body. The homogeneity of the cluster is tested by the calculation of the spectrum of Einstein frequencies. The total and the two partial pair distribution functions, the corresponding structure factors S(k) and the dynamical structure factor S(k, omega ) for longitudinal and transverse waves for a whole series of k vectors are calculated. S(k, omega ) allows the determination of the range of reasonably well defined dispersion relations.

Transport in nonhomogeneous superconductors

Most theoretical discussions of transport in superconductors in which the gap parameter Δ( r, t) varies in space and time have made use of local models or of time-dependent versions of the Ginzburg-Landau theory. The general non-local theory is difficult to treat mathematically, but progress is being made with use of Green's function methods and with use of the WKB method for solution of the Bogoliubov quasiparticle equations. Applications of the latter method to vortex lines in type-II superconductors and to flow normal to the N-S in the intermediate state of type-I superconductors will be discussed. Although complete solutions have not been obtained, it is possible to see qualitatively how the transition from super to normal flow occurs in the boundaries and how electric fields are set up to drive current through the normal regions with consequent dissipation.