Robert C. Albers

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A high-order multiple-scattering (MS) approach to the calculation of polarized x-ray-absorption spectra, which includes both x-ray-absorption ne structure (XAFS) and x-ray-absorption near-edge structure (XANES), is presented. EEcient calculations in arbitrary systems are carried out by using a curved-wave MS path formalism that ignores negligible paths, and(More)
We model a cubic-to-tetragonal martensitic transition by a Ginzburg-Landau free energy in the symmetric strain tensor. We show in three dimensions (3D) that solving the St. Venant compatibility relations for strain, treated as independent field equations, generates three anisotropic long-range potentials between the two order parameter components. These(More)
A long-standing problem in Pu science is the crystallographic mechanism for the delta-->alpha' (fcc-->monoclinic) transformation. Orientation relations between the two structures impose severe restrictions on the possible mechanisms and require the transition to be reconstructive, which we describe as a sequence of three displacive transitions:(More)
Since their discovery nearly a decade ago, plutonium-based superconductors have attracted considerable interest , which is now heightened by the latest discovery of superconductivity in PuCoIn5. In the framework of density functional theory (DFT) within the generalized gradient approximation (GGA) together with dynami-cal mean-field theory (DMFT), we(More)
We report an experimental determination of the dispersion of the soft phonon mode along [100] in uranium as a function of pressure. The energies of these phonons increase rapidly, with conventional behavior found by 20 GPa, as predicted by recent theory. New calculations demonstrate the strong pressure (and momentum) dependence of the electron-phonon(More)
The propagation of shock waves through polycrystalline iron is explored by large-scale atomistic simulations. For large enough shock strengths the passage of the wave causes the body-centered-cubic phase to transform into a close-packed phase with most structure being isotropic hexagonal-close-packed (hcp) and, depending on shock strength and grain(More)
I mpurities control phase stability and phase transformations in natural and man-made materials, from shape-memory alloys 1 to steel 2 to planetary cores 3. Experiments and empirical databases are still central to tuning the impurity eff ects. What is missing is a broad theoretical underpinning. Consider, for example, the titanium martensitic(More)
A minority-spin resonant state at the Fe/GaAs(001) interface is predicted to reverse the spin polarization with the voltage bias of electrons transmitted across this interface. Using a Green's function approach within the local spin-density approximation, we calculate the spin-dependent current in a Fe/GaAs/Cu tunnel junction as a function of the applied(More)