(gc3564)Nanostructure Formation, Aggregation, and Reactivity
EMSL Project ID
3564
Abstract
This project is the outgrowth of several projects currently funded by DOE-BES at PNNL and ANL or new proposals co-authored by the participants and submitted to DOE?s Computational Nanoscience initiative involving two complementary efforts that focus on the fundamental characterization of nanomaterials: their synthesis and their reactivity. These proposed studies draw on advanced and novel methodologies that are being developed in these projects and that are intended and designed to take full advantage of state-of-the-art computing capabilities such as those available at PNNL?s EMSL to broadly advance the field of modeling in nanoscience.The goal of the computational research on nanomaterial synthesis is to provide a comprehensive understanding of nucleation, growth, and aggregation relevant to nanotechnology through the application of simulation methods and tools, aiming at getting a handle on control of size, composition, structure, and properties of nanoscale building block components. Capabilities are being developed to understand, predict, and control production rate and characteristics of these fundamental building blocks and their dependence on external factors. Specific research subjects to be investigated in this are are: i) Molecular dynamics simulations of fullerene growth mechanisms by investigating the aggregation behavior of C2 molecular units under high temperature and pressure and subsequent cluster growth toward cage closure. ii) Molecular dynamics simulations for the interconversion of carbon onions into carbon spiroids. iii) The systematic simulation in parameter space (temperature and ionic concentration) of crystalline phase growth in solution, for example CdSe in organic solvent, for the fabrication of nano-electronic devices.
The goal of the computational research on nanomaterial reactivity is to obtain a characterization of reactivity in the nanoscale using several advanced and novel methods being developed. These new computational tools are specifically targeted at the quantum chemical characterization of structures, properties, and reactivity in the nanoscale. With the unique computing capabilities offered by the EMSL facility, these tools will provide the ability to carry out quantum chemical electronic structure calculations on systems heretofore not accessible, with up to 105 atoms, i.e. in the nano range, using a reliable and well calibrated reduced-requirement density functional-based tight binding method (DFTB). Embedding of this model into an physical and chemical environment to capture electronic and structural effects at different scales will be achieved through the coupling to the ONIOM protocol that permits combination of methods of variable fidelity, as well as a seamless approach, termed the Generalized Quasi-Continuum method (GQC), that couples fully resolved atomic scale regions with coarse-grained regions via a finite-element-like methodology, which will allow to investigate systems of up to several 1000 nm in size. The potential of the newly developed methods will be tested and benchmarked in selected studies dealing with the formation of nanosystems, their structure, and their reactivity. Specific research subjects to be investigated in this are are: i) Characterization of the formation mechanisms of carbon nanotubes and fullerenes from pure carbon and SiC compounds in the presence or absence of metal catalysts, and of their reactivity toward their oxidation and functionalization. ii) Characterization of the structure and thermal and non-thermal reactivity of metal/metal oxide nanoparticles (Cr2O3/Fe2O3, SrTiO3/Si) and of their catalytic activity (reaction specificity) as a function of their structure, composition, and size. iii) Characterization of thermal stability and growth of High-K material interfaces with silicon. iv) Investigation of the structures of nanoporous metal oxide (aluminum oxide, vanadium oxide) membranes and reactions pathways for catalytic reactions such as hydrocarbon dehydrogenation occurring on the surfaces of the pores.
Project Details
Project type
Capability Research
Start Date
2003-10-01
End Date
2006-10-08
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members