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  • 31.20.E  (1)
  • Atomic, Molecular and Optical Physics  (1)
  • SCF  (1)
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical chemistry accounts 86 (1993), S. 497-510 
    ISSN: 1432-2234
    Schlagwort(e): Parallel ; MIMD ; SCF ; Massively parallel computers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary One of the key methods in quantum chemistry, the Hartree-Fock SCF method, is performing poorly on typical vector supercomputers. A significant acceleration of calculations of this type requires the development and implementation of a parallel SCF algorithm. In this paper various parallelization strategies are discussed comparing local and global communication management as well as sequential and distributed Fock-matrix updates. Programs based on these algorithms are bench marked on transputer networks and two IBM MIMD prototypes. The portability of the code is demonstrated with the portation of the initial Helios version to other operating systems like Parallel VM/SP and PARIX. Based on the PVM libraries, a platform-independent version has been developed for heterogeneous workstation clusters as well as for massively parallel computers.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 13 (1989), S. 377-384 
    ISSN: 1434-6079
    Schlagwort(e): 31.15 ; 31.20.E
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract By using transputers it is possible to build up networks of parallel processors with varying topology. Due to the architecture of the processors it is appropriate to use the MIMD (multiple instruction multiple data) concept of parallel computing. The most suitable programming language is OCCAM. We investigate the use of transputer networks in computational chemistry, starting with the direct SCF method. The most time consuming step, the calculation of the two electron integrals is executed parallelly. Each node in the network calculates whole batches of integrals. The main program is written in OCCAM. For some large-scale arithmetic processes running on a single node, however, we used FORTRAN subroutines out of standard ab-initio programs to reduce the programming effort. Test calculations show, that the integral calculation step can be parallelized very efficiently. We observe a speed-up of almost 8 using eight network processors. Even in consideration of the scalar part of the SCF iteration, the speed-up is not less than 7.1.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 19 (1981), S. 113-130 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Semilocal pseudopotentials have been determined for first-row (Li to Ne), second row (Na to Ar), and third-row atoms (K, Ca). Core-valence correlation is included by adjusting the pseudopotentials to experimental energies of ions with a single valence electron. Correlation within the valence shell is taken into account by using the spin-density functional formalism. The approximations involved in this approach are tested for atomic ionization energies as well as binding energies of monohydrides and alkali diatomics, agreement with experiment is usually satisfactory, but in certain applications density functionals should be already included in the fitting of the local part of the pseudopotential. In addition, 3s/3p and 3s/2p basis sets (for first and second row, respectively), designed for use in connection with our pseudopotentials, are given; it is shown that they yield reasonable results for both SCF and correlation energies.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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