Aiichiro Nakano - US grants

This CAREER project in high performance computing and communications (HPCC) will develop an integrated research and education framework for predictive simulations of complex, real-life phenomena. The objective of this research project is to extend molecular dynamics (MD) simulations to larger system sizes, longer simulated times, and greater realism, through the use of new multilevel algorithms and novel models encompassing multiple levels of physical abstraction: i) space-time multiresolution schemes; ii) hierarchical dynamics via a rigid-body/implicit-integration/normal-mode approach; iii) adaptive curvilinear-coordinate load balancing; iv) variable valence MD based on electronegativity equalization; and v) multilevel preconditioned conjugate gradient method. Multimillion-atom MD simulations will be performed for multiscale phenomena in nanophase ceramics and metal-oxide nancomposites. The proposed research will impact advanced material technologies based on "multiscale structure control."

0085344
Kalia
This award supports a Focused Research Group at Louisiana State University for research and education on computational materials. The grant is jointly supported by the Division of Materials Research and the Division for Advanced Computational Infrastructure and Research and is a blend of condensed matter physics, materials science and computer science. The objective of the research is to understand how the bonding between dissimilar materials at the atomic level determines structure and macroscopic properties such as adhesion, friction, stiffness, and fracture toughness. The research will focus on: (1) ceramic composites (SiC fibers coated with silica in a Si3N4 matrix and aluminum oxide matrix containing aluminum oxide fibers coated with LaPO4); (2) metal/ceramic interfaces (Al/SiC and Ti/TiO2) and nanostructured composites of passivated metallic nanoparticles; and (3) oxidation, fracture and nanoindentation in these materials.

These applications require a methodology that can describe physical and mechanical processes over several decades of length scales. Quantum mechanical (QM) simulations based on the density functional theory will be preformed in regions where atomic bonds are formed or broken; molecular dynamics (MD) simulations will be carried out in nonlinear regions surrounding the QM region; and the finite-element (FE) approach with constitutive input from QM or MD calculations will be used in regions far away from the process zones. The QM, MD, and FE schemes will be integrated with an approach based on control theory. Algorithms will be designed to carry out these hybrid QM/MD/FE simulations in a metacomputing environment with multiple parallel machines, mass storage devices, and immersive and interactive virtual environments on a Grid with high-speed networks.

The Concurrent Computing Laboratory for Materials Simulation, where the research will be performed, has a record of innovative educational activities including a joint MS/PhD program in computer science and physics. Efforts are underway for a joint masters degree in computer science and applied physics. In addition, a web-based computational physics course is being taught simultaneously at LSU and the Delft University of Technology in The Netherlands. As part of this grant, a workshop will be established to mentor and recruit minority students.
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This award supports a Focused Research Group at Louisiana State University for research and education on computational materials. The grant is jointly supported by the Division of Materials Research and the Division for Advanced Computational Infrastructure and Research and is a blend of condensed matter physics, materials science and computer science. The objective of the research is to understand how the bonding between dissimilar materials at the atomic level determines structure and macroscopic properties such as adhesion, friction, stiffness, and fracture toughness.

The Concurrent Computing Laboratory for Materials Simulation, where the research will be performed, has a record of innovative educational activities including a joint MS/PhD program in computer science and physics. Efforts are underway for a joint masters degree in computer science and applied physics. In addition, a web-based computational physics course is being taught simultaneously at LSU and the Delft University of Technology in The Netherlands. As part of this grant, a workshop will be established to mentor and recruit minority students.
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EEC-0086508
Vashishta

The goal of this project is to understand atomistic processes involved in the constrained sintering of multilayered ceramic films and the mechanical properties of the sintered systems using large-scale molecular dynamics simulations. Research will focus on 1) ceramic/ceramic interfaces involving, Si3N4, SiC, and Al2O3 with amorphous SiO2 interlayers; and 2) sintering in laminated multilayer films consisting of nanoparticles of these ceramics with glassy coating. The objectives are to investigate: structure, stresses, friction, and debonding at interfaces; effects of thermal-expansion mismatch/anisotropy, nanoparticle size, and interfacial glassy layers on sintering; residual stress distribution; and delamination. Algorithms will be designed to carry out multiscale simulations combining the coarse-grained MD and the finite element methods in a metacomputing environment with multiple parallel machines, mass storage devices, and immersive and interactive virtual environments on a Grid with high speed networks.

The proposed research will have significant impact on new multilayer ceramic integrated circuit technologies in the electronic industry.

This award is the result of a proposal submitted to the Information Technology Research initiative. The goal of the research is to develop a scalable software infrastructure for large multiscale simulations on a Grid of geographically distributed, massively parallel supercomputers, as well as on future Petaflop computers.

The multiscale simulation approach will combine, in a single Grid software, finite element (FE) calculation, the coarse-grained molecular dynamics (CGMD), molecular dynamics (MD) simulation, and quantum mechanical (QM) calculation based on the density functional theory (DFT). Continuum mechanics calculation based on the FE method will be performed with constitutive relations derived from the CGMD method in conjunction with MD simulations, which in turn will embed QM algorithm described by the DFT. The following will be developed: (1) Grid-based FE/CGMD/MD/QM algorithms based on space-time multiresolution algorithms implemented with hierarchical decomposition on parallel/distributed computers for scalability and constrained-dynamics-based hybridization for seamless coupling of the hybrid simulation componets; (2) Space-time partitioned multiscale simulation combined with kinetic Monte Carlo (KMC) and parallel replica methods to couple disparate length and time scales; (3) Grid-computation tools including adaptive load balancing using wavelet-based computational-space decomposition and space-filling-curve-based adaptive data compression to reduce communication and storage; (4) Immersive and interactive visualization of the large simulation data using octree-based visibility culling and parallel/distributed preprocessing of the visualization data with machine-learning predictive prefetch.

The Gridified software will be used to study nanosystems of great importance to future information processing. Multiscale simulations involving 1,000 - 10,000 QM atoms and 100 million - 1 billion MD atoms will be performed to study atomistically-induced phenomena, with emphasis on environmental effects where chemical processes play an important role. The multiscale algorithm will relate the atomistic processes to experimentally observable quantities, by covering an order-of-magnitude larger length scale (10 micron) through continuum mechanics and extending time scales through the KMC and replica methods. The simulations will focus on stress domains and their phonon imaging in Si/Si3N4 and GaAs/Si3N4 nanopixels for sub-0.1 micron microelectronics applications and oxidation effects on them, and on substrate-encoded self-organized growth of lattice-mismatched semiconductor quantum dots (GaAs/InAs).

The project will involve close collaborations with scientists at government laboratories (Argonne, NASA Ames, Sandia, Naval Oceanographic Office), industry (Intel, Motorola) and universities, as well as international collaborations in Europe, Japan and South America.
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It is proposed to explore semiconductor nanocrystals such as quantum dots, rods and tetrapods, as templates for self-assembled 3D architectures of themselves and of core-shell nanocomposites . Multiscale simulations will be performed on Cd-S, Cd-Se, Zn-S, Ga-As, and In-As and their core shell nanocomposites. The relevant dimensional range in most cases will extend from the nanometer to the continuum, or part of it. They will be accomplished by a seamless combination of finite element continuum theories, molecular dynamics, and quantum mechanical calculations. Successful three-dimensional accounts of the resulting space distribution of atoms will yield a number of property and structural changes, at both bulk and atomistic levels. Among others, they will bring out the effects of nanocrystal size and shape, of organic molecules surface termination, and of nanoindentation testing on tetrapods and their arrays.
The multimillion-atom multiscale simulation will be displayed and steered in an immersive and interactive visualization program, its infrastructure being made available by the State of Louisiana . The three PIs have already accumulated an extensive practice with molecular dynamics applications (~10 million atoms). In addition, the they have initiated a close cooperative collaboration with Dr. Alivisatos' experimental program at the University of California- Berkeley. There are also plans to offer a number of cross disciplinary courses, leading to a dual-degree program ( physical/biological and computer sciences), to web-based global courses and to mentoring activities.
In summary, the PIs have accumulated an extensive experience in the field of parallel multiscale simulation, and have proceeded to obtain access to the corresponding high performance hardware and software. This should give them now a chance to test the behavior of a number of semiconductors, in a more diversified range of circumstances. To explore such a promising possibility, it is recommended that a one-year SCER award of $94,962 be granted, with a starting date of September 1, 2001.