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)
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 propose a new direct mechanism for the pressure driven ! ! martensitic transformation in pure titanium. A systematic algorithm enumerates all possible pathways whose energy barriers are evaluated. A new, homogeneous pathway emerges with a barrier at least 4 times lower than other pathways. The pathway is shown to be favorable in any nucleation model.(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)
An understanding of the phase diagram of elemental plutonium (Pu) must include both, the effects of the strong directional bonding and the high density of states of the Pu 5f electrons, as well as how that bonding weakens under the influence of strong electronic correlations. Here we present electronic-structure calculations of the full 16-atom per unit(More)
Martensitic phase transitions appear in a diverse range of natural and engineering material systems. Examination of the energetics and kinetics of the transformation requires an understanding of the atomic mechanism for the transformation. A systematic pathway generation and sorting algorithm is presented and applied to the problem of the titanium ␣ to ␻(More)
Equilibrium free energies for the ␣ and ␻ phases of Ti are constructed. The result is a consistent picture of the ambient pressure, static high pressure, and shock data, as well as first-principles electronic structure calculations. The Hugoniot consists of three segments: a metastable ␣-phase region, a transition region, and an ␻-phase branch. All the(More)