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  • 1
    Electronic Resource
    Electronic Resource
    Photoabsorption and photoemission of ozone in the Hartley band (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 6667-6675 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Theoretical calculations of ozone photoabsorption and photoemission in the Hartley band are presented. The potential energy surfaces of Sheppard and Walker [J. Chem. Phys. 78, 7191 (1983)] and of Barbe et al. [J. Mol. Spectrosc. 49, 171 (1974)] are used for the excited (1B2) and ground (1A1) states, respectively. In contrast with several recent studies, large amplitude motion in the symmetric and asymmetric stretch coordinates is explicitly included. Qualitative agreement is obtained with the experimental emission spectrum at 266 nm, although some discrepancies persists, using either the original Sheppard–Walker surface or various modifications thereof. Moreover, the calculations do not reproduce the experimentally observed structure atop the Hartley absorption band, eliminating some possibilities for the origin of this structure. The photofragmentation dynamics was computed by numerical integration of the time-dependent Schrödinger equation on a two-dimensional grid, and spectral observables were recovered via Fourier transform.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455339
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Massively parallel high-energy time-dependent wave-packet calculations (1991)
    Springer
    Theoretical chemistry accounts 79 (1991), S. 175-182 
    Details
    ISSN: 1432-2234
    Keywords: Wave packets ; Quantum dynamics ; Parallel computing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The exact solution of the time-dependent Schrödinger equation is obtained using a parallel implementation of the standard grid techniques. Most of the operations involved in this calculation may be executed concurrently for each of the grid points. For the few operations which may not be executed concurrently, we have implemented parallel algorithms. In our two-dimensional implementation on the Connection Machine, we have obtained optimal speed-up — that is, by usingN processors we achieve a speed-up which is proportional toN. In addition to the discussion of our 2-dimensional implementation, we shall discuss our proposed 3-dimensional implementation of these grid techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01113689
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Exact three-dimensional time-dependent wave packet calculations on the Connection Machine (1993)
    Springer
    Theoretical chemistry accounts 84 (1993), S. 335-342 
    Details
    ISSN: 1432-2234
    Keywords: Connection machine ; Single Instruction Multiple Data ; Time-dependent Schrödinger equation ; Wave packet calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In this paper, we report our massively parallel implementation of grid techniques for the solution of the time-dependent Schrödinger equation in three spatial dimensions on the Connection Machine, which is a Single Instruction Multiple Data (SIMD) computer. Most of the operations involved in this calculation may be executed independently for each grid point. The few operations which cannot be executed independently are implemented using parallel communication algorithms. In addition, we report a simple modification of the multidimensional FFT, which provides an estimated 15% reduction in computational complexity relative to the standard 2-D FFT. It is suggested that this modification may be very well suited to hypercube communication topologies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01113272
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Parallel pseudospectral electronic structure: I. Hartree-Fock calculations (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 19 (1998), S. 1017-1029 
    Details
    ISSN: 0192-8651
    Keywords: pseudospectral ; parallel ; Hartree-Fock ; gradient ; scalable ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We present an outline of the parallel implementation of our pseudospectral electronic structure program, Jaguar, including the algorithm and timings for the Hartree-Fock and analytic gradient portions of the program. We also present the parallel algorithm and timings for our Lanczos eigenvector refinement code and demonstrate that its performance is superior to the ScaLAPACK diagonalization routines. The overall efficiency of our code increases as the size of the calculation is increased, demonstrating actual as well as theoretical scalability. For our largest test system, alanine pentapeptide [818 basis functions in the cc-pVTZ(-f) basis set], our Fock matrix assembly procedure has an efficiency of nearly 90% on a 16-processor SP2 partition. The SCF portion for this case (including eigenvector refinement) has an overall efficiency of 87% on a partition of 8 processors and 74% on a partition of 16 processors. Finally, our parallel gradient calculations have a parallel efficiency of 84% on 8 processors for porphine (430 basis functions).   © 1998 John Wiley & Sons, Inc.   J Comput Chem 19: 1017-1029, 1998
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Parallel pseudospectral electronic structure: II. Localized Møller-Plesset calculations (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 19 (1998), S. 1030-1038 
    Details
    ISSN: 0192-8651
    Keywords: pseudospectral ; parallel ; localized Møller-Plesset, scalable ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We have developed a parallel version of our pseudospectral localized Møller-Plesset electronic structure code. We present timings for molecules up to 1010 basis functions and parallel speedup for molecules in the range of 260-658 basis functions. We demonstrate that the code is scalable; that is, a larger number of nodes can be efficiently utilized as the size of the molecule increases. By taking advantage of the available distributed memory and disk space of a scalable parallel computer, the parallel code can calculate LMP2 energies of molecules too large to be done on workstations.   © 1998 John Wiley & Sons, Inc.   J Comput Chem 19: 1030-1038, 1998
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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