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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 84 (1993), S. 301-314 
    ISSN: 1432-2234
    Keywords: Parallel direct SCF ; Quantum chemistry ; MPSCF ; LAN
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Quantum chemistry has become an essential tool in many areas of chemical research; however, quantum chemistry is not yet playing a role in many exciting new chemical disciplines, such as medicinal chemistry and materials science, where the size of the chemical systems has been too large to study usingab initio chemical methods. The development of massively parallel supercomputers offers the potential to predict properties relevant to a variety of problems in these burgeoning new fields. The goal of this project is to develop a set of parallelized “production codes” for initially a relatively limited set of methods. As a key part of this project we are experimenting with the use of modern programming languages and methodologies to make these programs both portable and reusable. This paper describes the development of a massively parallel direct SCF program, MPSCF. For systems over a few hundred basic functions, MPSCF running on 256 nCUBE processors performs nearly as well as Gaussian 90 running on a single processor Cray Y-MP. On the next generation of parallel computers, such as the Intel Touchstone Delta, MPSCF should allow the SCF calculations on chemical systems too large for vector supercomputers.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 44 (1992), S. 277-290 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We compare three global configuration search methods on a scalable model problem to measure relative performance over a range of molecule sizes. Our model problem is a 2-D polymer composed of atoms connected by rigid rods in which all pairs of atoms interact via Lennard-Jones potentials. The global minimum energy can be calculated analytically. The search methods are all hybrids combining a global sampling algorithm with a local refinement technique. The sampling methods are simulated annealing (SA), genetic algorithms (GA), and random search. Each of these uses a conjugate gradient (CG) routine to perform the local refinement. Both GA and SA perform progressively better relative to random search as the molecule size increases. We also test two other local refinement techniques in addition to CG, coupled to random search as the global method. These are simplex followed by CG and simplex followed by block-truncated Newton. For small problems, the addition of the intermediate simplex step improved the performance of the overall hybrid method. © 1992 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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