Deepak Srivastava Computational Nanotechnology at CSC/NAS NASA Ames Research Center

1. Computational Nanotechnology of Materials, Devices and Machines: Carbon Nanotubes Deepak Srivastava Computational Nanotechnology at CSC/NAS NASA Ames Research Center Moffett Field, CA 95014 Collaborators: M. Menon – University of Kentucky K. Cho – Stanford University D. Brenner – NC State University R. Ruoff – Northwestern University M. Osman – Washington State University

3. http://www.ipt.arc.nasa.gov at Ames Research Center

4. Simulation Techniques • Large scale Classical Molecular Dynamics Simulations on a Shared • Memory Architecture Computer • Tersoff-Brenner reactive many-body potential for hydrocarbons • with long range LJ(6-12) Van der Walls interactions • Parallel implementation on a shared memory Origin2000 • Quantum Molecular Dynamics Simulations • Tight-binding MD in a non-orthogonal atomic basis • Previous parametrization: silicon and carbon (M. Menon and K. R • Subbaswami, Phys. Rev. B 1993-94. • Extended to heteroatomic systems including C, B, N, H

5. Experimental Nanotechnology at Ames Research Center http://www.ipt.arc.nasa.gov at Ames Research Center

6. Nanomechanics of Nanomaterials • Nanotubes are extremely strong highly elastic nanofibers ~ High value of Young’s Modulus (1.2 -1.3 T Pa for SWNTs) ~ Elastic limit upto 10-15% strain • Dynamic response under axial compression, bending torsion • redistribution of strain • sharp buckling leading to bond rupture • SWNT is stiffer than MWNT

7. Nanomechanics of Nanomaterials

8. Nanotubes in Composites • Experiment: buckling and collapse of nanotubes embedded • in polymer composites. Local collapse or fracture of thin tubes. Buckle, bend and loops of thick tubes..

9. Stiffness and Plasticity of Compressed C Nanotubes

10. Plastic Collapse of an (8,0) Carbon Nanotube Quantum Molecular Dynamics • D. Srivastava, M. Menon and K. Cho, Phys. Rev. Lett. (1999)

11. Plastic Collapse by Design • Tube plastically collapses at the location of the defect • New types of heterojunctions can be created • Quantum dot effect in one dimensional system

12. CxByNz Nanotubes • Band gap engineering over a larger range • BN ~ 5 eV • BC2N ~ 2 eV • C ~ 0 - 1 eV • BC3 ~ 0.5 eV

13. BN Nanotubes - Structural Characteristics • BN bond buckling effect:

14. BN Nanotubes: Nanomechanics and Plasticity • Comparison of Young’s modulus and elastic limit

15. Anisotropic Plasticity of BN Nanotube • Plastic collapse at 14.75% strain (a) (b) (c) (d) (e)

16. Anisotropic Plasticity of BN Nanotubes Quantum Molecular Dynamics

17. Comparison of Plastic Collapse of BN and C Anisotropic strain release Isotropic strain release

18. BN Nanotubes - Nanomechanics • BN nanotube based composite with anisotropic plasticity • Nanostructured skin effect !

20. Nanotube Electronics (Basics)

21. Band Structure

25. Nanoelectronics with Doping

28. Nano Electromechanical Effects (NEMS) Mechanical deformation alter the electronic deformation Of nanotubes : effect is chirality dependent

29. Mechano-Chemical Effects: Kinky Chemistry Cohesive Energy Binding Energy

30. Functionalization of Nanotubes

31. Mechano-Chemical Effects: Kinky chemistry SEM images of MWNTs dispersed on a V-ridged Formvar substrate D. Srivastava, J. D. Schall, D. W. Brenner, K. D. Ausman, M. Feng And R. Ruoff, J. Phys. Chem. Vol. 103, 4330 (1999).

32. Molecular Machines and Laser Motor J. Han, A Globus and R. Jaffe

33. Molecular Machines and Laser Motor

34. Computational Nanotechnology: PSE Nanomanipulation in Virtual World Simulations Experiments Next Generation of Technology and Products

35. Comments • compressed C nanotube nanomechanics in composites • BN nanotube is almost as stiff as a C nanotube with even higher • elastic limit • anisotropicplastic collapse is observed • ~ nanostructured skin effect • ~ functionality of a smart material • concept of a mechanical kink catalyzed chemistry of flexible • nanoscale materials • ~ kinky chemistry