Showing papers by "Elena F. Sheka published in 2002"
TL;DR: A parallel implementation of the conventionally used N DDO and modified NDDO-WF techniques for semiempirical quantum chemical calculations of large molecular systems in the sp- and spd-basis is described and the atom-pair distribution of data over processors forms the basis of the parallelization.
Abstract: A parallel implementation of the conventionally used NDDO (MNDO, AM1, PM3, CLUSTER-Z1) and modified NDDO-WF (CLUSTER-Z2) techniques for semiempirical quantum chemical calculations of large molecular systems in the sp- and spd-basis, respectively, is described. The atom-pair distribution of data over processors forms the basis of the parallelization. The technological aspects of designing scalable parallel calculations on supercomputers (using ScaLAPACK and MPI libraries) are discussed. The scaling of individual algorithms and the entire package was carried out for model systems with 894, 1920, and 2014 atomic orbitals. The package speed-up provided by different multiprocessor systems involving a cluster of Intel PIII processors, Alpha-21264-processor-built machine MBC-1000M, and Cray-T3E is analyzed. The effect of computer characteristics on the package performance is discussed. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
24 citations
TL;DR: In this article, the high-spin states of the Si60 fullerene and its oligomers are considered semi-empirically by using sequential and parallel implementations of the AM1 codes.
Abstract: High-spin states of the Si60 fullerene and its oligomers are considered semiempirically by using sequential and parallel implementations of the AM1 codes. The states are energetically favorable and nearly degenerated over triplet, quintet, and septet spins. All atoms of the Si60 fullerene are in sp3-configuration, which is supported by atomic spin density in addition to electron density, the latter to be responsible for the formation of chemical bonds. Spotted distribution of spin density over atoms provides molecular magnetism of the molecule. A similar picture is disclosed for oligomers {Si60}n with n up to 8, which according to computational results should be magnetic with a fractal-like distribution of spin density over atoms. Opposite the latter, composites Si60C60 and Si60H60 behave conventionally and are nonmagnetic. A way of the Si60 fullerene synthesizing is suggested via the above composite product as intermediates. The considered oligomers are proposed as a model of silicon nanofibers observed recently. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
20 citations
01 Jan 2002
TL;DR: In this article, a parallel implementation of the conventionally used NDDO (MNDO, AM1, PM3, CLUSTER-Z1) techniques for semi-empirical quantum chemical calculations of large molecular systems in the sp- and spd-basis is described.
Abstract: A parallel implementation of the conventionally used NDDO (MNDO, AM1, PM3, CLUSTER-Z1) and modified NDDO-WF (CLUSTER-Z2) techniques for semiempirical quantum chemical calculations of large molecular systems in the sp- and spd-basis, respectively, is described. The atom-pair distribution of data over processors forms the basis of the parallelization. The technological aspects of designing scalable parallel calculations on supercomputers (using ScaLAPACK and MPI libraries) are discussed. The scaling of individual algorithms and the entire package was carried out for model systems with 894, 1920, and 2014 atomic orbitals. The package speed-up provided by different multiprocessor systems involving a cluster of Intel PIII processors, Alpha-21264-processor-built machine MBC-1000M, and Cray-T3E is analyzed. The effect of computer characteristics on the package performance is discussed. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
18 citations