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  • 1
    Electronic Resource
    Electronic Resource
    A generalized non-muffin-tin theory of band structureThis work was supported by the U.S. Army Research Office. (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 87-104 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A generalized non-muffin-tin band structure method is presented in the context of multiple scattering off of the Wigner-Seitz cell. This technique has the following desirable features: it is formally exact and rapidly convergent; it preserves the separation between the nondiagonal scattering matrix for the cell and the usual structure constants of KKR in the secular determinant; it produces an accurate representation of the wave function throughout the sphere bounding the Wigner-Seitz cell and hence is suitable for self-consistent field calculations and applications that require a detailed knowledge of the unperturbed crystal potential and wave functions. Various aspects of the application of this theory to the empty lattice and sodium are presented, and its limitations discussed. Some future lines of research are briefly reviewed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260813
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Statistical microdynamics of extended systems in natural function spaces (1993)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 48 (1993), S. 363-375 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An approximate numerical method of solving the Generalized Master Equation for a many-body problem is presented, with examples of its application. This method involves the construction from the full Hamiltonian (of the system plus the “bath”) of a set of unitary Langevin equations that combine deterministic microcanonical, stochastic canonical (heat bath), and stochastic nonthermal dynamics in a single time-integration scheme. If implemented in a representation that captures the essential physics and repeatedly run from a given initial condition, this method evaluates stochastic representatives from the actual fiber bundle of system worldlines that flow from the initial condition and, hence, numerically evaluates the path integral. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560480837
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  • 3
    Electronic Resource
    Electronic Resource
    A generalized non-muffin-tin theory of band structure (1985)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 27 (1985), S. 803-804 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560270614
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  • 4
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    Convection and segregation in directional solidification of dilute and non-dilute binary alloys - Effects of ampoule and furnace design (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A Petrov-Galerkin/finite-element method is used to analyze the effect of furnace configuration and ampoule design on the temperature field, the convection in the melt, the shape of the melt-solid interface, and the segregation of solute in the crystal, in the directional solidification of several dilute and nondilute binary semiconductor alloys. The vertical Bridgman-Stockbarger system leads to a two-cell flow structure, and the constant gradient furnace has only a single cell near the interface. Radial temperature gradients interact with the solute field to cause the previously predicted sideways diffusive instability, and addition of a solute that is less dense than the bulk melt and that is incorporated upon solidification decreases the intensity of the flow near the interface by increasing the melt density there. The present results have application to understanding of the effects on solute segregation of microgavity solidification and of applied magnetic fields.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 80; 155-190
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  • 5
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    Effect of vertical magnetic field on convection and segregation in vertical Bridgman crystal growth (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A previous finite-element analysis of vertical Bridgman growth for dilute and nondilute alloys is extended to include the effect of a vertically-aligned magnetic field in the limit of zero magnetic Reynolds number. Calculations are presented for growth of a dilute gallium-germanium alloy in a vertically stabilized Bridgman-Stockbarger system and in a furnace with a uniform temperature gradient imposed along the ampoule. Steady cellular convection driven by radial temperature gradients causes good axial and radial mixing in both systems without a magnetic field. A weak magnetic field decreases the intensity of convection and the effectiveness of solute mixing. The radial nonuniformity is greatest for an intermediate field strength. Stronger fields suppress flow recirculation completely, and lead to uniform solute segregation across the crystal and to diffusion-controlled axial segregation.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 89; 2-3,; 339-356
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  • 6
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    Models for convection and segregation in the growth of HgCdTe by the vertical Bridgman method (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Transport processes in the vertical Bridgman growth of Hg(1-x)Cd(x)Te were investigated by numerical analysis of an idealized quasi-steady-state model of this system. The analysis was specifically directed at an explanation for the radial and axial segregation data obtained by Szofran and Lehoczky (1984) and Szofran et al. (1984) on this system, who reported, respectively, on the observations of diffusion-controlled axial segregation and on the presence of large compositional nonuniformities of CdTe across the radius of the crystal. It is shown that the data sets of these groups can be explained by the results of a detailed analysis of heat transfer, convection, and species transport which account for thermosolutal convection in the melt and for heat transfer mechanisms that dominate the HgCdTe alloy. Predictions from this analysis is applicable to the growth of other materials, because they suggest conditions for the growth of radially uniform crystals with nearly constant axial composition profiles.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 96; 3, Ju; 609-627
    Format: text
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  • 7
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    Modelling of the dynamics of HgCdTe growth by the vertical Bridgman method (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-08-14
    Description: The analysis of Kim and Brown (1989), which described the pseudo-steady state of the HgCdTe melt/crystal system grown by the vertical Bridgman method, is extended to the study of the transients during the crystal growth and, in particular, at the beginning of the growth. The time-dependent numerical simulations developed show the development of a diffusion layer in the melt and the direct relationship between this layer and the intensity and the pattern of convection in the melt. It is shown that the spread of the solute layer occurs on a diffusive time scale, with the initial transient to the steady-state growth rate lasting several hours for the slow growth rates that are typical of the HgCdTe growth. The simulations demonstrate all the features observed experimentally by Szofran et al. (1984).
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 114; 3, No; 411-434
    Format: text
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