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Improvements on the direct SCF method

Authors

  • Marco Häser,

    1. Institut für Physikalische Chemie und Elektrochemie, Lehrstuhl f. Theoretische Chemie, Universität Karlsruhe Kaiserstr. 12, D-7500 Karlsruhe, West Germany (FRG)
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  • Reinhart Ahlrichs

    1. Institut für Physikalische Chemie und Elektrochemie, Lehrstuhl f. Theoretische Chemie, Universität Karlsruhe Kaiserstr. 12, D-7500 Karlsruhe, West Germany (FRG)
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Abstract

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.

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