Chirality-Dependent Properties of Carbon Nanotubes. Electronic Structure: Optical Dispersion Properties, Hamaker Coefficients and van der Waals - London dispersion interactions
Optical dispersion spectra at energies up to 30 eV play a vital role in understanding the chirality-dependent van der Waals London dispersion interactions of single wall carbon nanotubes (SWCNTs). We use one-electron theory based calculations to obtain the band structures and the frequency dependent...
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Zusammenfassung: | Optical dispersion spectra at energies up to 30 eV play a vital role in
understanding the chirality-dependent van der Waals London dispersion
interactions of single wall carbon nanotubes (SWCNTs). We use one-electron
theory based calculations to obtain the band structures and the frequency
dependent dielectric response function from 0-30 eV for 64 SWCNTs differing in
radius, electronic structure classification, and geometry. The resulting
optical dispersion properties can be categorized over three distinct energy
intervals (M, pi, and sigma, respectively representing 0-0.1, 0.1-5, and 5-30
eV regions) and over radii above or below the zone-folding limit of 0.7 nm.
While pi peaks vary systematically with radius for a given electronic structure
type, peaks are independent of tube radius above the zone folding limit and
depend entirely on SWCNT geometry. Based on these calculated one-electron
dielectric response functions we compute and review Van derWaals - London
dispersion spectra, full spectral Hamaker coefficients, and van derWaals -
London dispersion interaction energies for all calculated frequency dependent
dielectric response functions. Our results are categorized using a new optical
dielectric function classification scheme that groups the nanotubes according
to observable trends and notable features (e.g. the metal paradox) in the 0-30
eV part of the optical dispersion spectra. While the trends in these spectra
begin to break down at the zone folding diameter limit, the trends in the
related van derWaals - London dispersion spectra tend to remain stable all the
way down to the smallest single wall carbon nanotubes in a given class. |
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DOI: | 10.48550/arxiv.1211.0001 |