Edge States and magnetism in carbon nanotubes with line defects.
(2008)
Journal - Physical review letters (United States )
Abstract :
We apply first-principles calculations to investigate the interplay between electronic and magnetic properties of carbon nanotubes with line defects. We consider three types of defects: lines of C--O--C epoxy groups, and defects resulting from the substitution of the oxygen atoms by CH2 or C2H4 divalent radicals. We find that the line defects behave as pairs of coupled graphene edge states, and a variety of electronic and magnetic ground states is predicted as a function of defect type, nanotube diameter, and a possibly applied transverse electric field.
Small polarons in dry DNA.
(2003)
Journal - Physical review letters (United States )
Abstract :
We report ab initio calculations for positively charged fragments of dry poly(dC)-poly(dG) DNA, with up to 4 C-G pairs. We find a strong hole-lattice coupling and clear evidence for the formation of small polarons. The largest geometry distortions occur in only one or two base pairs. They involve the stretching of weak bonds within each base pair, increasing the distance of positive hydrogens, and decreasing that of negative oxygens, to the region in which the hole localizes. We obtain an energy of approximately 0.30 eV for the polaron formation, nearly independent of the chain size. From it, we can estimate an activation energy for polaron hopping of approximately 0.15 eV, consistent with the available experimental value.
| ISSN : | 0031-9007 |
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| Mesh Heading : | Base Pairing DNA Models, Chemical Models, Molecular Polydeoxyribonucleotides Thermodynamics |
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| Mesh Heading Relevant : | chemistry chemistry |
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