NASA Sponsored Computational Nanotechnology Project:

Principal Investigators

Accomplishments

In the following, we list the projects undertaken (completed, and ongoing) over the 1998 funding year for the NASA sponsored Computational Nanotechnology Project.

The FY 1997 report described the accomplishments and ongoing efforts in various project areas. The accounts of the completed work have appeared in refereed journals during 1998, [1-4]. The following list describes the work brought to completion (or being extended), for which the papers are submitted (accepted or currently under consideration) or presented in conferences, during the FY 1998.

• The computational nanotechnology effort at the Materials and Proccess Simulation Center is described in detail in a review article which appears in the inaugural issue (January 1999) of Journal of Nanoparticle Research [5].

• The development of generalized empirical bond order dependent hydrocarbon potentials is completed and resulting work is in press [6].

• Molecular and supramolecular assembly: We have continued on working on self assembly of dendritic polymers. The results of this work are reviewed in a book chapter [7].

• Transport Phenomena at the nanoscale: We have studied the transport phenomena for nanotubes, fullerenes and diamond using nonequilibrium molecular dynamics (NEMD). The calculated thermal conductivities are found in good agreement with the experiment using the new generalized empirical bond order potentials [8].

• Tribology: Friction, Wear, and viscosity: We have used a steady state MD method to study the friction and wear properties of diamond surfaces [9].

• Friction and viscosity of confined lubricants: Using the same technique, we also studied the visco-elastic properties of lubricants confined between the self assembled monolayers of wear inhibitors dithiophosphates (DTP) and dithiocarbametes (DTC) on iron oxide surfaces [10].

• Plasticity and deformation behavior: Using the steady state MD method and generalized bond order dependent potentials for hydrocarbons, we studied deformation behavior of fullerene nanotubes [8] and metalic nanowires [11] described by a many body potential [12].

• Diamond mechanosynthesis and the surface reactions in Silicon and Diamond: Using ab initio methods during the last year, we have investigated various surface reaction mechanism for diamond and silicon [13].

Education, training and outreach

The postdoctoral scholar, Dr. Jianwei Che focusing solely on the carbon-fullerene nanotechnology and on the nanotribology of MEMS and NEMS devices based on diamond and polycrystalline diamond.

A graduate student, Ms. Yue Qi and a visiting scientist, Prof. Hideyuki Ikeda, have focused on the characterization of metalic nanowires, their phase transformations and deformation behavior.

Two graduate students, Mr. Ryan Martin and Guofeng Wang, focused on macromolecular self assembly problems and working on deendritic polymers and their use in nanotechnology areas.

Senior investigators have presented research results in the computational nanotechnology project at various conferences and participated in national research policy forums held on nanotechnology.

Personnel and Collaborators

Ongoing Projects

• Supramolecular Assembly: The convergent and divergent synthetic methods developed for dendrimers have substantial potential in the design of tailored hyperbranched structures for use in molecular nanotechnology applications. We will try to understand the self assembly of dendrimers on surfaces as possible nano- or micro scale sensor applications on one hand and on the other hand we will investigate their metal encapsulation properties. Metal encapsulation, and subsequent manipulation of dendrimers through AFM or self assembly processes will be investigated for feasibility of constructing self assembled ordered quantum dot arrays.

• Inherent Tribological Properties of Nanoscale Materials We will continue to investigate friction and wear properties of diamond and silicon surfaces using ab initio techniques and in MD simulation we will focus on surfaces other than (100) and the surfaces with asperities.

• Formation of fullerenes and nanotubes:Using the new potentials we are studying the formation of fullerenes, onions and nanotubes from long time scale MD simulations.

• Metals in low dimensions The properties of nanoscopiclally thin films, nano-wires and nano-dots made up off metals will be studied using many body quantum Sutton Chen potentials.

Requested Funding for Year 3

Citations

1. G. Gao, T. Cagin, and W.A. Goddard, III, Position of K atoms in doped single walled carbon nanotube crystals, Phys. Rev. Lett., 80, 5556 (1998).
2. T. Cagin, A. Jaramillo-Botero, G. Gao, and W. A. Goddard, III, Molecular Mechanics and Molecular Dynamics Analysis of Drexler-Merkle Gears and Neon Pump, Nanotech. 9 (3), 143-152 (1998).
3. G. Gao, T. Cagin, W. A. Goddard, III, Energetics, structure, thermodynamic and mechanical properties of nanotubes, Nanotech. 9 (3) 183-191 (1998).
4. S. Walch and R. Merkle, "Theoretical studies of reactions on diamond surfaces," Nanotech. 9 (3) 285-96 (1998).
5. T. Cagin, J. Che, Y. Qi, Y. Zhou, E. Demiralp, G. Gao, and W. A. Goddard III, Computational materials chemistry at the nanoscale, Journal of Nanoparticle Research, in press.
6. Jianwei Che, Tahir Cagin, and William A. Goddard III, Generalized Extended Empirical Bond-Order Dependent Force Fields Including Nonbond Interactions, Thermochim. Acta, in press.
7. T. Cagin, P. J. Miklis, G. Wang, G. Zamanakos, R. Martin, H. Li, D. T. Mainz, V. Nagarajan, and W. A. Goddard, III, Recent Advances in Simulation of Dendritic Polymers, in Dynamics in Small Confining Systems V Eds. J. M. Drake, G. S. Grest, J. Klafter, and R. Kopelman, in press.
8. J. Che, T. Cagin, W. A. Goddard, III, Studies of Fullerenes and Carbon Nanotubes by an Extended Bond Order Potential presented at the 1998 Foresight Conference on Molecular Nanotechnology, considered for publication in Nanotechnology(1998).
9. T. Cagin, J. Che, M. N. Gardos, A. Fijany, W. A. Goddard, III, Simulation and Analysis of Experiments on Friction and Wear of Diamond: A material for MEMS and NEMS applications presented at the 1998 Foresight Conference on Molecular Nanotechnology, considered for publication in Nanotechnology(1998).
10. T. Cagin, Y. Zhou, E. S. Yamaguchi, R. Frazier, A. Ho, Y. Tang, and W. A. Goddard III, Simulation of Thermal Stability and Friction: A lubricant confined between Monolayers of Wear Inhibitors on Iron Oxide, in Dynamics in Small Confining Systems V Eds. J. M. Drake, G. S. Grest, J. Klafter, and R. Kopelman, in press.
11. H. Ikeda, Y. Qi, T. Cagin, K. Samwer, W.L. Johnson, W. A. Goddard, III, Strain rate induced amorphisation in metalic nanowires, Phys. Rev. Lett., submitted (1998).
12. Y. Kimura, T. Cagin, Y. Qi and W. A. Goddard III, The Quantum Sutton Chen Many-Body Potentials for Properties of fcc Metals, Phys. Rev. B1, submitted (1998).
13. S. P. Walch, W. A. Goddard, III, and T. Cagin, Computational Studies of the Interaction of H/H2 with Diamond and Silicon Surfaces presented at the 1998 Foresight Conference on Molecular Nanotechnology, considered for publication in Nanotechnology(1998).