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Multi-Center Electronic Structure Calculations for Plasma Equation of State

Description: We report on an approach for computing electronic structure utilizing solid-state multi-center scattering techniques, but generalized to finite temperatures to model plasmas. This approach has the advantage of handling mixtures at a fundamental level without the imposition of ad hoc continuum lowering models, and incorporates bonding and charge exchange, as well as multi-center effects in the calculation of the continuum density of states.
Date: December 14, 2010
Creator: Wilson, B. G.; Johnson, D. D. & Alam, A.
Partner: UNT Libraries Government Documents Department
open access

The energetics and electronic origins for atomic long- and short-range order in Ni-Fe invar alloys

Description: States of magnetic and compositional order are strongly coupled in many magnetic alloys, with Ni-Fe Invar being the most celebrated example. Results of an electronic-based method that addresses compositional and magnetic disorder, as well as atomic short-range order and energetics, are discussed. This allows a system-dependent microscopic understanding of the interplay of chemical, magnetic, and displacive effects, and a direct comparison to diffuse scattering experiments. Discussion is in cont… more
Date: December 31, 1996
Creator: Johnson, D. D. & Shelton, W. A.
Partner: UNT Libraries Government Documents Department
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First-principles calculation of the magnetic properties of paramagnetic fcc iron

Description: Using the disordered local moment picture of itinerant magnetism, we present calculations of the temperature and volume dependence of the magnetic moment and spin-spin correlations for fcc Fe in the paramagnetic state. These calculations are based on the parameter-free, first principles approach of local spin density functional theory and the coherent potential approximation is used to treat the disorder associated with the random orientation of the local moments.
Date: January 1, 1985
Creator: Johnson, D. D.; Gyorffy, B. L.; Pinski, F. J.; Staunton, J. & Stocks, G. M.
Partner: UNT Libraries Government Documents Department
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The electronic structure and the state of compositional order in metallic alloys

Description: Many two-component (A,B) systems crystallize into a random solid solution. In such a state the atoms occupy a more or less regular array of lattice sites but each site can be A or B in a random fashion. Then, on lowering the temperature, the system will either phase separate or order, starting at some transition temperature T/sub c/. The aim of these lectures is to present a microscopic approach to the understanding of these scientifically interesting and technologically important processes. 64… more
Date: January 1, 1987
Creator: Gyorffy, B. L.; Johnson, D. D.; Pinski, F. J.; Nicholson, D.M. & Stocks, G. M.
Partner: UNT Libraries Government Documents Department
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Self-Consistent Electronic Structure of Alpha-Phase Hume-Rothery Electron Compound Alloys Cu/sub C/Zn/sub 1-C/, Cu/sub C/Ga/sub 1-C/, and Cu/sub C/Ge/sub 1-C/

Description: We have performed charge self-consistent electronic structure calculations for the ..cap alpha..-phase Hume-Rothery electron compound alloys Cu/sub c/Zn/sub 1-c/, Cu/sub c/Ga/sub 1-c/, and Cu/sub c/Ge/sub 1-c/ having electron to atom ratios 1:1, 1:2, and 1:3 for each alloy series. The calculations are based on the self-consistent-field Korringa-Kohn-Rostoker coherent-potential approximation (KKR-CPA). We show results for the densities of states and Fermi surface of these alloys; the behavior of… more
Date: January 1, 1985
Creator: Stocks, G. M.; Boring, A. M.; Nicholson, D. M.; Pinski, F. J.; Johnson, D. D.; Faulkner, J. S. et al.
Partner: UNT Libraries Government Documents Department
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The origins of ordering in CuPt

Description: The alloy CuPt is one of the few that order into a L1{sub 1} crystal structure, i.e. planes of copper and planes of planes of planes of platinum perpendicular to the < 111 > direction. For disordered CuPt, the calculated Warren-Cowley short-range order parameter indicates an instability to concentration fluctuations with a wave-vector of ({1/2}, {1/2}, {1/2}), consistent with L1{sub 1} ordering. We show that this rare tendency is due to this ordering vector arising from the large joint density … more
Date: August 4, 1993
Creator: Clark, J. F.; Pinski, F. J.; Sterne, P. A.; Johnson, D. D.; Staunton, J. B. & Ginatempo, B.
Partner: UNT Libraries Government Documents Department
open access

First principles simulation of materials properties

Description: We have developed a hybrid, parallel computer code for calculating the electronic structure of both ordered and substitutionally disordered materials. By using PVM3.3, we can integrate into our local computer environment multiple parallel and vector superconductors as well as high performance workstations. Without this approach, calculations of materials properties of large systems would be otherwise untenable due to a lack of computer resources. For example, we have determined the short-range … more
Date: June 1, 1994
Creator: Shelton, W. A.; Stocks, G. M.; Pinski, F. J.; Jordan, R. G.; Liu, Y.; Qui, L. L. et al.
Partner: UNT Libraries Government Documents Department
open access

First principles simulation of materials properties

Description: We have developed a hybrid, parallel computer code for calculating the electronic structure of both ordered and substitutionally disordered materials. By using PVM3.3, we can integrate into our local computer environment multiple parallel and vector supercomputers as well as high performance workstations. Without this approach, calculations of materials properties of large systems would be otherwise untenable due to a lack of computer resources. For example, we have determined the short-range o… more
Date: August 1, 1994
Creator: Shelton, W. A.; Stocks, G. M.; Jordan, R. G.; Liu, Y.; Qui, L.; Johnson, D. D. et al.
Partner: UNT Libraries Government Documents Department
open access

Competing mechanisms for ordering tendencies in BCC CuAuZn{sub 2} and FCC AuFe alloys

Description: We have briefly discussed the ASRO (atomic short-range order) in AuFe and CuAuZn{sub 2}. General points are that (1) we have implemented a first-principles theory of ASRO in N-component alloys which allows determination of the electronic origins of said ASRO; (2) such calculations can provide much information on the high- and (sometimes) low-temperature alloys; and (3) this approach has identified the origin for the novel special-point ASRO in AuFe. Displacement effects, i.e., non-rigid lattice… more
Date: July 1, 1995
Creator: Johnson, D. D.; Althoff, J. D.; Staunton, J. B.; Ling, M. F. & Pinski, F. J.
Partner: UNT Libraries Government Documents Department
open access

On the causes of compositional order in the Ni sub c Pt sub (1-c) alloys

Description: We review, briefly, the arguments which gave rise to the current controversy concerning the origin of compositional order in Ni{sub c}Pt{sub 1-c} alloys. We note that strain fluctuations play an important role in determining the state of compositional order in this system and outline a theoretical framework that takes account of them. 29 refs., 4 figs.
Date: January 1, 1991
Creator: Gyorffy, B.L. (Bristol Univ. (United Kingdom). H.H. Wills Physics Lab.); Pinski, F.J. (Cincinnati Univ., OH (United States). Dept. of Physics); Ginatempo, B. (Messina Univ. (Italy). Ist. di Fisica Teorica); Johnson, D.D. (Sandia National Labs., Albuquerque, NM (United States)); Staunton, J.B. (Warwick Univ., Coventry (United Kingdom). Dept. of Physics); Shelton, W.A. et al.
Partner: UNT Libraries Government Documents Department
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