Embedded microclusters in zeolites and cluster beam sputtering: Simulation on parallel computers. Annual progress report, September 15, 1992--September 14, 1993
An optimal time-space multi-resolution approach has been designed to carry out large-scale molecular-dynamics (MD) simulations on distributed-memory MDM (Multiple Instructions Multiple Data) machines. The multi-resolution MD approach was used to investigate structural correlations in porous silica. Structural parameters such as internal surface area and surface-to-volume ratio of pores, pore size distribution, fractal dimension, and mean particle size have been calculated over a wide range of densities. Simulation results are in accordance with structural measurements. Molecular-dynamics simulations were also performed to provide a microscopic understanding of recent pioneering high-pressure experiments on silica glasses at NSLS. The simulations reveal a structural transition to a new high-pressure amorphous phase with corner- and edge-sharing SiO{sub 6} octahedra. Parallel algorithms were designed for an initio quantum dynamics approach to materials simulations. With this approach, we have investigated the nature of electron transport in materials. We have also developed a tight-binding MD approach to investigate the influence of orientational disorder on structural correlations and phonon spectra of C{sub 60} solid. Results agree with neutron-scattering measurements. Currently, large-scale NM simulations ({approximately} 10{sup 6} atoms) are being performed to investigate the relation between structure, dynamics, and mechanical properties and the influence of environment, composition, and stress conditions on nanophase ceramics (Si{sub 3}N{sub 4}, SiC, TiO{sub 2}, and Al{sub 2}O{sub 3}), and on silicates, aluminosilicates, and zeolites.
- Research Organization:
- Louisiana State Univ., Baton Rouge, LA (United States). Concurrent Computing Lab. for Materials Simulations
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG05-92ER45477
- OSTI ID:
- 10184447
- Report Number(s):
- DOE/ER/45477--1; ON: DE94000741
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360000
99 GENERAL AND MISCELLANEOUS
990200
CERAMICS
COMPUTER CALCULATIONS
COMPUTERIZED SIMULATION
DYNAMICS
FULLERENES
MATERIALS
MATHEMATICS AND COMPUTERS
PARALLEL PROCESSING
PHASE STUDIES
PHONONS
POROUS MATERIALS
PROGRESS REPORT
QUANTUM MECHANICS
SILICON OXIDES
SUPERCOMPUTERS
ZEOLITES