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  • 1990-1994  (4)
  • 1
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 508-517 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: A method for accurate and efficient local density functional calculations (LDF) on molecules is described and presented with results. The method, Dmol for short, uses fast convergent three-dimensional numerical integrations to calculate the matrix elements occurring in the Ritz variation method. The flexibility of the integration technique opens the way to use the most efficient variational basis sets. A practical choice of numerical basis sets is shown with a built-in capability to reach the LDF dissociation limit exactly. Dmol includes also an efficient, exact approach for calculating the electrostatic potential. Results on small molecules illustrate present accuracy and error properties of the method. Computational effort for this method grows to leading order with the cube of the molecule size. Except for the solution of an algebraic eigenvalue problem the method can be refined to quadratic growth for large molecules.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 7245-7250 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Analytical energy gradients for numerical orbital expansions can be calculated using the same three-dimensional integration methods as for calculating the total energy in the local-density-functional approach. It is shown that in addition to Pulay corrections for expansion functions attached to the atomic sites correction terms for non-self-consistency of the auxiliary density can also be used with benefit. The usefulness of this approach is demonstrated in the calculation of equilibrium geometries of organic and inorganic molecules, radicals, and transition-metal compounds. The calculated structural parameters are in at least as good agreement with experimental data as structures obtained from standard ab initio methods. Excellent basis sets can be used at a comparably low computational cost.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1573-4900
    Schlagwort(e): Density functional theory ; Electronic structure calculation ; Parallel computing ; Clusters ; Surface adsorption and dissociation ; Defects ; Catalysts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Summary This article gives a brief overview of density functional theory and discusses two specific implementations: a numerical localized basis approach (DMol) and the pseudopotential plane-wave method. Characteristic examples include Cu, clusters, CO and NO dissociation on copper surfaces, Li-, K-, and O-endohedral fullerenes, tris-quaternary ammonium cations as zeolite template, and oxygen defects in bulk SiO2. The calculations reveal the energetically favorable structures (estimated to be within ± 0.02 Å of experiment), the energetics of geometric changes, and the electronic structures underlying the bonding mechanisms. A characteristic DMo1 calculation on a 128-node nCUBE 2 parallel computer shows a speedup of about 107 over a single processor. A plane-wave calculation on a unit cell with 64 silicon atoms using 1024 nCUBE 2 processors runs about five times faster than on a single-processor CRAY YMP.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Hyperfine interactions 64 (1991), S. 743-748 
    ISSN: 1572-9540
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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