designing carbon-based nanotechnology on a supercomputer · acknowledgements financial support:...
TRANSCRIPT
![Page 1: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/1.jpg)
[email protected]://www.pa.msu.edu/~tomanek
Designing CarbonDesigning Carbon--BasedBasedNanotechnology Nanotechnology on a Supercomputeron a Supercomputer
David TomDavid TomááneknekMichigan State UniversityMichigan State University
![Page 2: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/2.jpg)
Acknowledgements
Financial Support:
Gianaurelio Cuniberti, University of RegensburgYoshiyuki Miyamoto, N.E.C. Tsukuba, JapanNorbert Nemec, University of RegensburgAngel Rubio, University of Pais Vasco, Spain
NSF-NSEC JAMSTEC-ESC (Japan)NSF-NIRT RIST (Japan)
![Page 3: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/3.jpg)
OutlineIntroduction− Carbon nanotubes: Ideal building blocks for nanotechnology?− Computational toolsCan computation guide nanomanufacturing?− What limits the frequency response of nanotube electronics?− How to best contact a carbon nanotube?− How to cure atomic-scale defects?Summary and Conclusions
Printed Review:David Tománek, Carbon-based nanotechnology on a supercomputer, Topical Review inJ. Phys.: Condens. Matter 17, R413-R459 (2005).
![Page 4: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/4.jpg)
Nanocarbon pioneersThe C60 ‘buckyball’ and other fullerenes:
- successful synthesis- potential applications:
lubricationsuperconductivity
Nanotubes:- successful synthesis- potential applications:
composites flat-panel displaysLi-ion batteries super-capacitorsmedication delivery fuel cellsEMI shielding hydrogen storage
Nanotubes in the core of carbon fibers:
A. Oberlin, M. Endo, and T. Koyama,
J. Cryst. Grow. 32 (1976) 335-349
![Page 5: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/5.jpg)
Carbon nanotubes:Ideal building blocks for nanotechnology?
1-20 nm diameterAtomically perfectChemically inert100 times stronger than steelExtremely high melting
temperatureIdeal (ballistic) conductors of
electrons, or insulatorsIdeal heat conductorsNon-toxic
![Page 6: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/6.jpg)
Ground state dynamics:Solve the eigenvalue problem:
nnnH ψεψ =
Density Functional Theory(codes including SIESTA, VASP, CASTEP, GAUSSIAN, etc.)
Excited state dynamics:Solve the time-dependent problem:
nn H
dtdi ψψ
=h
First-Principles Simulation tool for Electron-Ion Dynamics
First-Principles Simulation tool for Electron-Ion Dynamics
Based on time-dependent density functional theory (TDDFT):E. Runge and E. K. U. Gross, Phys. Rev. Lett. 52, 997 (1984).
Computational details for real-time MD simulations:Sugino & Miyamoto PRB 59, 2579 (1999) ; ibid, B 66, 89901(E) (2002),using the Suzuki-Trotter split operator method to compute the time-propagator
|e>
|g>
Reaction coordinate
Pot
entia
l
What approach to use?
Computational Approach to Nanostructures
Need massively parallel computer architectures and suitable algorithms distribute load over processors for speed-up
![Page 7: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/7.jpg)
Computational Nanotechnology Computational Nanotechnology Laboratory:Laboratory:
Earth Simulator, TokyoEarth Simulator, Tokyo
Cost: $500,000,000Maintenance: $50,000,000/year<70% used fornano-carbons
![Page 8: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/8.jpg)
OutlineIntroduction− Carbon nanotubes: Ideal building blocks for nanotechnology?− Computational toolsCan computation guide nanomanufacturing?− What limits the frequency response of nanotube electronics?− How to best contact a carbon nanotube?− How to cure atomic-scale defects?Summary and Conclusions
Printed Review:David Tománek, Carbon-based nanotechnology on a supercomputer, Topical Review inJ. Phys.: Condens. Matter 17, R413-R459 (2005).
![Page 9: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/9.jpg)
Can computation guide nanomanufacturing?
Nanotube
Nanotube Field Effect Transistor
What limits the speed of nanotube-based electronics?How to best contact a carbon nanotube?Are nanotube devices as sensitive to defects as Si-LSI circuits?Are there ways to selectively remove defects?
![Page 10: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/10.jpg)
Choi, Ihm, Louie, Cohen, PRL (2000)
Quantum conductance of a (10,10) nanotube with a single vacancy
Perfect tube
Defective tube
Dangling bonds: σelectrons
Missing network of πelectrons
Individual defects significantly degrade conductance of a nanotube
![Page 11: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/11.jpg)
What limits the frequency response of nanotube electronics?How useful are carbon nanotube devices(field-effect transistors, non-linear optical devices)?
Maximum switching frequency:➨ lifetime of excited carriersHow long do electronic excitations last?What dampens electronic excitations:
•Electron gas?•Phonons?
Nanotube
Nanotube Field Effect Transistor
Experiment: T. Hertel and G. Moos, PRL 84, 5002 (2000)
Interpretation:e-e comes before e-ph
![Page 12: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/12.jpg)
Relaxation of hot carriers after a photo-excitation
![Page 13: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/13.jpg)
Which metal-nanotube contacts optimize charge injection?
• Short, strong contact?
• Long, weak contact?
• Fermi momentum conservation?
Norbert Nemec, David Tománek, and Gianaurelio Cuniberti, Phys. Rev. Lett. 96, 076802 (2006).
How to best contact a carbon nanotube?
Nanotube
Nanotube Field Effect Transistor
![Page 14: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/14.jpg)
Δρ(r) = ρC&Pd(r) - ρC(r) - ρPd(r)Δρ(r) = ρC&Ti(r) - ρC(r) - ρTi(r)
• Charge redistribution in Pd/graphite and Ti/graphite:
• Electronic structure of Pd/C:DOS
ΔDOS
Pd/graphite:Carrier injection with Fermi momentum of graphite seems possible
![Page 15: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/15.jpg)
Pd (better)
Ti (worse)
T•Transmission loss ΔT:
Lc smallΔ large
Lc largeΔ small
•Optimum contacts are weak and long•Certain metals (Pd) are preferred over others (Ti, Au)
•Model of nanotube interacting with metal leads
![Page 16: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/16.jpg)
HO
By chemical treatment with H?By heat treatment?⇒No: Larger damage to nanotube
How to cure atomic-scale defects?How to deoxidize?
Y. Miyamoto, N. Jinbo, H. Nakamura, A. Rubio, and D. Tománek, Phys. Rev. B 70, 233408 (2004).
![Page 17: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/17.jpg)
O
O-related electronic levels
O2p
O2s
Electronic excitations!Alternative to thermal and chemical treatment
![Page 18: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/18.jpg)
O2s
O2p
CNT V.B.
C.B.
hopelessO2s → O2p excitation (33 eV)
![Page 19: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/19.jpg)
30 fs
60 fs126 fs
H2
Auger decay following the O1s → 2p excitation (~520 eV)
CNT V.B.
O1s
O2s
O2p
C.B.
♦Photoexcitations are long-lived ♦Deoxidation by photo-surgery
![Page 20: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/20.jpg)
URL: http://endomoribu.shinshu-u.ac.jp/nt06/or: http://nanotube.msu.edu/nt06/
Seventh International Conference on theScience and Application of Nanotubes
Hotel Metropolitan Nagano
Nagano, Japan June 18-23, 2006
![Page 21: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/21.jpg)
Summary and ConclusionsSelected technological challenges in nanotube-based electronics can be best understood and solved by combining time-dependent DFT simulations with classical MD simulations.Electronic excitations in nanotubes exhibit ultrafast dynamics and decay by electronic and phonon channels.Optimum nanotube-metal contacts are long and strongly depend on the element, not the morphology. Photo-excitations are very long-lived and can be used to selectively remove oxygen impurities and heal other defects.
![Page 22: Designing Carbon-Based Nanotechnology on a Supercomputer · Acknowledgements Financial Support: Gianaurelio Cuniberti, University of Regensburg Yoshiyuki Miyamoto, N.E.C. Tsukuba,](https://reader034.vdocuments.us/reader034/viewer/2022042323/5f0d04ef7e708231d43846d1/html5/thumbnails/22.jpg)
The End