|
Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. October 2004, Volume 3, Number 10, 651-661 |
Calculations of Electronic Absorption Spectra and Third-order
Polarizabilities of Finite Open Single-wall Carbon Nanotubes of
(4,2) with Different Lengths
Wen-Dan Cheng, Dong-Sheng Wu, Xiao-Dong Li, You-Zhao Lan, Ya-Jing Gong, Da-Gui Chen, and Yong-Chun Zhang
Internet Electron. J. Mol. Des. 2004, 3, 651-661
|
Abstract:
The subjects of electronic absorption and dynamic third-order
polarizability spectra of (4,2) carbon nanotubes are studied when
the 1D system is made small and converged to tube length of about
one nm size. Also the main contributions to optical nonlinearities
of the studied system are explored. B3LYP formalism is carried
out for the geometry optimization and time-dependent B3LYP is
used to calculate electronic absorption spectra. With the
combination of SOS method, the third-order polarizabilities are
calculated. There is a larger gap, blue shift of absorption spectra,
smaller third-order polarizabilities in tube axial direction, and
smaller anisotropy of polarizability spectra in a shorter finite open
(4,2) tubes. Electron transitions from the π bonding to π
antibonding orbitals make a significant contribution to the low
energy absorption spectrum and third-order polarizability for the
(4,2) tubes. The largest third-order polarizability is in the direction
of the polarized and basic light along with the tube axis, and these
polarizabilities originate from the one-photon allowed excitation states.
|