Calculation of Potential Energy for Fe Atom around Entrance of (10,0) Carbon Nanotube

Kudo, Yohei; Hira, Takahisa; Ishii, Soh; Morisato, Tsuguo; Ohno, Kaoru

doi:10.2320/matertrans.47.2462

Cited by 1 publication

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“…The radial and angular parts of the atomic orbitals were obtained by solving the atomic Kohn–Sham equation numerically and by spherical harmonics, respectively. The accuracy and validity of this method were demonstrated in our previous study on the interaction between an iron (Fe) atom and an open-ended SWNT. , We used the double numerical basis set with polarization functions (DNP). Basically, when a basis set is localized on atoms, as in the DMol 3 code, different configurations will have different basis sets, which introduces error in the calculations.…”

Section: Methodsmentioning

confidence: 99%

Encapsulation of Carbon Chain Molecules in Single-Walled Carbon Nanotubes

Kuwahara

Kudo

Morisato³

et al. 2011

J. Phys. Chem. A

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The vacuum space inside carbon nanotubes offers interesting possibilities for the inclusion, transportation, and functionalization of foreign molecules. Using first-principles density functional calculations, we show that linear carbon-based chain molecules, namely, polyynes (C(m)H(2), m = 4, 6, 10) and the dehydrogenated forms C(10)H and C(10), as well as hexane (C(6)H(14)), can be spontaneously encapsulated in open-ended single-walled carbon nanotubes (SWNTs) with edges that have dangling bonds or that are terminated with hydrogen atoms, as if they were drawn into a vacuum cleaner. The energy gains when C(10)H(2), C(10)H, C(10), C(6)H(2), C(4)H(2), and C(6)H(14) are encapsulated inside a (10,0) zigzag-shaped SWNT are 1.48, 2.04, 2.18, 1.05, 0.55, and 1.48 eV, respectively. When these molecules come inside a much wider (10,10) armchair SWNT along the tube axis, they experience neither an energy gain nor an energy barrier. They experience an energy gain when they approach the tube walls inside. Three hexane molecules can be encapsulated parallel to each other (i.e., nested) inside a (10,10) SWNT, and their energy gain is 1.98 eV. Three hexane molecules can exhibit a rotary motion. One reason for the stability of carbon chain molecules inside SWNTs is the large area of weak wave function overlap. Another reason concerns molecular dependence, that is, the quadrupole-quadrupole interaction in the case of the polyynes and electron charge transfer from the SWNT in the case of the dehydrogenated forms. The very flat potential surface inside an SWNT suggests that friction is quite low, and the space inside SWNTs serves as an ideal environment for the molecular transport of carbon chain molecules. The present theoretical results are certainly consistent with recent experimental results. Moreover, the encapsulation of C(10) makes an SWNT a (purely carbon-made) p-type acceptor. Another interesting possibility associated with the present system is the direction-controlled transport of C(10)H inside an SWNT under an external field. Because C(10)H has an electric dipole moment, it is expected to move under a gradient electric field. Finally, we derive the entropies of linear chain molecules inside and outside an open-ended SWNT to discuss the stability of including linear chain molecules inside an SWNT at finite temperatures.

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Section: Methodsmentioning

confidence: 99%