Microscopic theory of the rhombohedral phase and transition to the monoclinic phase of solid<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">C</mml:mi></mml:mrow><mml:mrow><mml:mn>70</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Николаев, А. В.; Michel, K. H.

doi:10.1103/physrevb.54.12733

Cited by 4 publications

(1 citation statement)

References 33 publications

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“…The set of potential constants used here is a modification of the set used in Ref. 25 and is tabulated in Table I. Note that in the present description, the carbon nanotube does not exhibit bond ICs, i.e., the 70+ 20+ 30 ICs of the C 70 molecule interact only with the tube's C atoms.…”

Section: ͑24͒mentioning

confidence: 99%

Nanotube field and orientational properties ofC70molecules in carbon nanotubes

Verberck

Michel

2007

Phys. Rev. B

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The orientation of a C 70 fullerene molecule encapsulated in a single-walled carbon nanotube ͑SWCNT͒ depends on the tube radius. First we confirm that chirality effects do not affect the orientation as well by comparing discrete atomistic calculations with the results of a continuous tube approximation for a variety of SWCNTs. The molecular and the tube symmetry are exploited by using symmetry-adapted rotator functions. We accurately determine the optimal molecular orientation as a function of the tube radius; for low ͑Շ7 Å͒ and high ͑տ7.2 Å͒ tube radii, lying and standing molecular orientations are recovered, respectively. In between, we observe a transition regime. In addition, we consider off-axis positions. We perform a one-dimensional liquid description of a chain of on-axis C 70 molecules inside a SWCNT. All results agree well with recent x-ray diffraction experiments.

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Section: ͑24͒mentioning

confidence: 99%

Nanotube field and orientational properties ofC70molecules in carbon nanotubes

Verberck

Michel

2007

Phys. Rev. B

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Charge transfer and polymer phases in AC60 (A=K, Rb, Cs) fullerides

Николаев

Prassides

Michel

1998

The Journal of Chemical Physics

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Starting from a microscopic model of interactions in A+C60− crystals, where A+ is an alkali metal ion and C60− the molecular ion, we present a theory of the phase transitions from the orientationally disordered Fm3̄m structure to polymer and dimer phases. The electronic charge transfer is accounted for by the t1u molecular orbitals of C60−. The resulting Coulomb interactions between neighboring C60− and between C60− and the sublattice of alkali metal ions lead to new orientation dependent potentials which have to be added to the intermolecular pair potential and to the crystal field. By studying the orientation dependence of the crystal field and the molecular field, we find that, in comparison with the phase transition Fm3̄m→Pa3̄ known from C60-fullerite, additional channels to a Pmnn structure with subsequent polymerization and dimerization are opened. We study the symmetry of the low temperature phases and compare with experimental results. The present work comprises an extension of the formalism of rotator functions to molecular orbitals.

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Coupling of orientational and translational modes in solid C₆₀and C₇₀

Lamoen¹,

Michel²

1999

Phase Transitions

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The orientational phase transitions in solid C60 and C70 are accompanied by-quite different anomalies in the crystalline strains. In solid C~O the phase transition Fm3m + Pa3 is primarily an orientational effect (antiferro-rotational), which is driven by the condensation of orientational modes belonging to X: irreducible representation (irreps) of Fmjm. These modes are the primary order parameters (oops) and their number is equal to the number of i m p s of Tzg and T I , symmetry within the manifolds under consideration. Taking into account irreps up to the manifold I= 12, we have studied the rotation-rotation-translation (RRT) coupling between the oops and the lattice displacements. We have investigated the resulting lattice contraction and the change of the elastic constant c1I at the phase transition. In solid C70 (fcc-phase) we investigate the bilinear coupling of orientational fluctuations of Tzg symmetry to transverse acoustic lattice displacements. This coupling is the driving mechanism for the ferroelastic phase transition Fm3m + Rjm. Finally we investigate the transition from the rhombohedra1 phase to a low temperature monoclinic phase. This transition in antiferro-rotational.

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Microscopic theory of the rhombohedral phase and transition to the monoclinic phase of solidC70

Cited by 4 publications

References 33 publications

Nanotube field and orientational properties ofC70molecules in carbon nanotubes

Nanotube field and orientational properties ofC70molecules in carbon nanotubes

Charge transfer and polymer phases in AC60 (A=K, Rb, Cs) fullerides

Coupling of orientational and translational modes in solid C₆₀and C₇₀

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Microscopic theory of the rhombohedral phase and transition to the monoclinic phase of solidC70

Cited by 4 publications

References 33 publications

Nanotube field and orientational properties ofC70molecules in carbon nanotubes

Nanotube field and orientational properties ofC70molecules in carbon nanotubes

Charge transfer and polymer phases in AC60 (A=K, Rb, Cs) fullerides

Coupling of orientational and translational modes in solid C60and C70

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Product

Resources

About

Coupling of orientational and translational modes in solid C₆₀and C₇₀