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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. January 2004, Volume 3, Number 1, 29-36 |
Low-Lying Transition-Allowed States of Tube-Like Fullerenes C60+10n
Yasushi Nomura, Hiroya Fujita, Susumu Narita, and Tai-ichi Shibuya
Internet Electron. J. Mol. Des. 2004, 3, 29-36
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Abstract:
Several groups have theoretically shown that the
HOMO-LUMO gaps of the tube-like fullerene C60+10n vary
periodically with n and take minimum values at n = 2, 5, ....
Previously we demonstrated similar periodicity for their
lowest excitation energies. Here we examine the low-lying
excited states from the spectroscopic viewpoint. SECI (or
TDA) calculations are made in the semiempirical CNDO/S
approximation. The geometries optimized with Gaussian 98
at the AM1 level are used. The excitation energy of the
lowest transition-allowed state of the C60+10n is shown to vary
periodically with n. In the simulated absorption spectra for
n > 3, prominent peaks with large oscillator strengths appear
at the low energy region (< 3 eV). Their peak positions also
similarly vary with n. It is found that two SEC's of
[HOMO → LUMO+1] and [HOMO-1 → LUMO] make dominant
contributions to both the lowest allowed state and the excited
state corresponding to the prominent peak. The periodic
n-dependences of the lowest transition-allowed excitation
energy and of the prominent peak position are direct
reflections of those of the two SEC's including HOMO and LUMO.
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