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Full-Text Articles in Physics

Accuracy And Limitations Of Localized Green’S Function Methods For Materials Science Applications, Duane D. Johnson, Andrei V. Smirnov Dec 2001

Accuracy And Limitations Of Localized Green’S Function Methods For Materials Science Applications, Duane D. Johnson, Andrei V. Smirnov

Duane D. Johnson

We compare screened real-space and reciprocal-space implementations of Korringa-Kohn-Rostoker electronic-structure method for their applicability to largescale problems requiring various levels of accuracy. We show that real-space calculations in metals can become impractical to describe energies. We suggest a combined r- and k-space scheme as the most efficient and flexible strategy for accurate energy calculations. Our hybrid code is suitable for (parallel) large-scale calculations involving complex, multicomponent systems. We also discuss how details of numerical procedures can affect accuracy of such calculations.


Classical Density Functional Theory Of Freezing In Simple Fluids: Numerically Induced False Solutions, M. Valera, F. J. Pinski, Duane D. Johnson Nov 2001

Classical Density Functional Theory Of Freezing In Simple Fluids: Numerically Induced False Solutions, M. Valera, F. J. Pinski, Duane D. Johnson

Duane D. Johnson

Density functional theory (DFT) has provided many insights into the freezing of simple fluids. Several analytical and numerical solution have shown that the DFT provides an accurate description of freezing of hard spheres and their mixtures. Compared to other techniques, numerical, grid-based algorithms for solving the DFT equations have more variational freedom and are capable of describing subtle behavior, as that seen in mixtures with multipeaked density profiles. However the grid-based approach is sensitive to the coarseness of the mesh employed. Here we summarize how the granularity of the mesh affects the freezing point within the DFT. For coarse meshes ...


Composite Magnetostrictive Materials For Advanced Automotive Magnetomechanical Sensors, R. William Mccallum, Kevin W. Dennis, David C. Jiles, John E. Snyder, Y. H. Chen Apr 2001

Composite Magnetostrictive Materials For Advanced Automotive Magnetomechanical Sensors, R. William Mccallum, Kevin W. Dennis, David C. Jiles, John E. Snyder, Y. H. Chen

Ames Laboratory Publications

In this paper we present the development of a composite magnetostrictive material for automotive applications. The material is based on cobaltferrite,CoO⋅Fe2O3, and contains a small fraction of metallic matrix phase that serves both as a liquid-phasesintering aid during processing and enhances the mechanical properties over those of a simple sinteredferrite ceramic. In addition the metal matrix makes it possible to braze the material, making the assembly of a sensor relatively simple. The material exhibits good sensitivity and should have high corrosion resistance, while at the same time it is low in cost.


Magnetic Force Microscopy Study Of Magnetization Reversal In Sputtered Fesial(N) Films, Chester C.H. Lo, J. E. Snyder, J. S. Leib, R. Chen, B. Kriegermeier-Sutton, Matthew J. Kramer, David C. Jiles, M. T. Kief Mar 2001

Magnetic Force Microscopy Study Of Magnetization Reversal In Sputtered Fesial(N) Films, Chester C.H. Lo, J. E. Snyder, J. S. Leib, R. Chen, B. Kriegermeier-Sutton, Matthew J. Kramer, David C. Jiles, M. T. Kief

Materials Science and Engineering Publications

The magnetization reversal in a series of rf-sputtered FeSiAl(N) films has been studied using magnetic force microscopy. A system has been developed which has the capability to image domain structure while an in-plane magnetic field is applied in situ. All films exhibited a stripe domain structure in zero applied field which was indicative of a perpendicular component of domain magnetization which alternates in sign. All films showed a similar sequence of magnetization processes: on reducing the applied field from saturation a fine stripe domain structure nucleated and then coarsened as the field was decreased to zero. Local switching of ...