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  • 1
    Electronic Resource
    Electronic Resource
    Møller-Plesset (MP2) perturbation theory for large molecules (1993)
    Springer
    Theoretical chemistry accounts 87 (1993), S. 147-173 
    Details
    ISSN: 1432-2234
    Keywords: Correlation ; MP2 ; AO ; Laplace transform ; Bounds ; Parallel computer ; Gradient ; Crystal ; Solid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A novel formulation of MP2 theory is presented which starts from the Laplace transform MP2 ansatz, and subsequently moves from a molecular orbital (MO) representation to an atomic orbital (AO) representation. Consequently, the new formulation is denoted AO-MP2. As in traditional MP2 approaches electron repulsion integrals still need to be transformed. Strict bounds on the individual MP2 energy contribution of each intermediate four-index quantity allow to screen off numerically insignificant integrals with a single threshold parameter. Implicit in our formulation is a bound to two-particle density matrix elements. For small molecules the computational cost for AO-MP2 calculations is about a factor of 100 higher than for traditional MO-based approaches, but due to screening the computational effort in larger systems will only grow with the fourth power of the size of the system (or less) as is demonstrated both in theory and in application. MP2 calculations on (non-metallic) crystalline systems seem to be a feasible extension of the Laplace transform approach. In large molecules the AO-MP2 ansatz allows massively parallel MP2 calculations without input/output of four-index quantities provided that each processor has in-core memory for a limited number of two-index quantities. Energy gradient formulas for the AO-MP2 approach are derived.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01113535
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Komplexe mit Phosphor und Arsen als terminalen LigandenDiese Arbeit wurde vom Fonds der Chemischen Industrie und von der Deutschen Forschungsgemeinschaft gefördert. Prof. Dr. R. Ahlrichs sei für wertvolle Kommentare gedankt, seinen Mitarbeitern K. Eichkorn und E. Weigend für die Überlassung noch unpublizierter Basissätze. (1996)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 108 (1996), S. 2637-2641 
    Details
    ISSN: 0044-8249
    Keywords: Arsenidokomplexe ; Komplexe mit Pnictidliganden ; Phosphidokomplexe ; Wolframverbindungen ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19961082110
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Improvements on the direct SCF method (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 10 (1989), S. 104-111 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Three improvements on the direct self-consistent field method are proposed and tested which together increase CPU-efficiency by about 50%: (i) selective storage of costly integral batches; (ii) improved integral bond for prescreening; (iii) decomposition of the current density matrix into a linear combination of previous density matrices - for which the two-electron contributions to the Fock matrix are available - and a remainder ΔD, which is minimized; construction of the current Fock matrix only requires processing of the small ΔD which enhances prescreening.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540100111
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    Paper (German National Licenses)
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