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| Author(s): |
Antonio Claudio Michejevs Padilha
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Física (IF/SBI) |
| Defense date: | 2011-09-22 |
| Examining board members: |
Maria Cristina dos Santos;
Ana Claudia Monteiro Carvalho;
Rosangela Itri
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| Advisor: | Maria Cristina dos Santos |
| Abstract | |
Carbon Nanotubes and conducting polymers are strong candidates for use in nanoscale electronic devices. Theoretical studies claimed that 1/3 of the nanotubes are metallic, while the others are semiconductors, but some groups have reported experimental measurements of a small electronic gap in tubes considered metallic. Prototype transistors made of nanotubes and organic conjugated molecules were proposed and it has been noticed that the coverage of the tubes by pentacene molecules made those trasistors less susceptible to impurity deposition, reducing the hysteresis in the characteristic I x V curve, while the formation of pentacene cristals was favored. In this work, we studied the electronic structure of the nanotubes (5,5) and (9,0) using DFT and noticed an electronic gap in those systems, as well as a deformation of their structures, similar to a Peierls distortion. The effect of the Hartree-Fock exchange included in the B3LYP functional was studied, as we varied its weight to obtain some properties of those systems. Later, we used molecular mechanics and classical molecular dynamics with the CVFF 950 force field and obtained structures compatible with pentacene crystals around the tubes, showing that the tubes in fact favor the formation of of these structures around them. (AU) | |
| FAPESP's process: | 09/06823-3 - Pentacene-carbon nanotube clusters: a theoretical MM/QM study |
| Grantee: | Antonio Cláudio Michejevs Padilha |
| Support Opportunities: | Scholarships in Brazil - Master |