Simulation of molecular and electronic structure of polyhydrogenated (n,0)-tubulenes and their analogs intercalated with lithium |
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Authors: | E G Gal'pern I V Stankevich A L Chistyakov L A Chernozatonskii |
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Institution: | (1) A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 ul. Vavilova, 117813 Moscow, Russian Federation;(2) N. M. Emanuel' Institute of Biochemical Physics, Russian Academy of Sciences, 4 ul. Kosygina, 117334 Moscow, Russian Federation |
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Abstract: | Molecular and electronic structure of four polyhydrogenated (n,0)-tubulenes, namely, −C24H4−]
m
(1), two isomers of composition −C28H4−]
m
(2 and3), and −C32H4−]
m
(4) withn benzene rings in the cross section (n=6, 7, 7, and 8, respectively), was simulated atm>1 (m is the number of repeating fragemnts). It was assumed that hydrogen atoms are attached to all carbon atoms lying on the two
most distant elements of the cylinders of the corresponding tubulenes. The energy band structures of macromolecules1–4 and their Li-intercalated analogs −C24H4Li−]
m
(5) −C28H4Li−]
m
(two isomers,6 and7), and −C32H4Li−]
m
(8), containing one Li atom per repeating unit at each center, were obtained in the EHT approximation by the crystal orbital
method. Geometric parameters of repeating units of structures1–8 were found after MNDO/PM3 optimization of the energies of hydrocarbon molecules C72H24, C84H26 (two geometric isomers), and C96H28, containing three repeating units of corresponding tubulenes1–4 each. The conductivity types of polyhydrogenated tubulenes1–4 are the same as those of their precursors, (6,0)-, (7,0)-, and (8,0)-tubulenes. Dispersion curves of systems5–8 are much the same as those of macromolecules1–4; however, electron energy spectra of5–8 possess metallic conductivity type and the positions of Fermi levels for these systems are higher than for compounds1–4.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2061–2067, November, 1999. |
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Keywords: | tubulenes (carbon nanotubes) polyhydrogenated tubulenes polyhydrogenated tubulenes intercalated with Li molecular mechanics method quantum-chemical calculations EHT approximation crystal orbital method MNDO/PM3 method |
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