Hard numbers on soft matter

Rydberg, Henrik; Jacobson, Niclas; Hyldgaard, Per; Simak, Sergei I.; Lundqvist, Bengt I.; Langreth, David C.

doi:10.1016/s0039-6028(03)00109-2

Cited by 87 publications

(121 citation statements)

References 30 publications

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“…The many opportunities in biological systems, in organic-molecular liquids and in the carbon nanostructures motivate a continuous search for a consistent combination of traditional DFT and vdW corrections. This biophysics and nanotechnology perspective motivated our recent proposal for a vdW-DF for layered systems [1,2,3,4].…”

Section: Introductionmentioning

confidence: 90%

Van der Waals interactions of parallel and concentric nanotubes

Schröder

Hyldgaard

2003

Materials Science and Engineering: C

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For sparse materials like graphitic systems and carbon nanotubes the standard density functional theory (DFT) faces significant problems because it cannot accurately describe the van der Waals interactions that are essential to the carbon-nanostructure materials behavior. While standard implementations of DFT can describe the strong chemical binding within an isolated, single-walled carbon nanotube, a new and extended DFT implementation is needed to describe the binding between nanotubes. We here provide the first steps to such an extension for parallel and concentric nanotubes through an electron-density based description of the materials coupling to the electrodynamical field. We thus find a consistent description of the (fully screened) van der Waals interactions that bind the nanotubes across the low-electron-density voids between the nanotubes, in bundles and as multiwalled tubes.

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Section: Introductionmentioning

confidence: 90%

Van der Waals interactions of parallel and concentric nanotubes

Schröder

Hyldgaard

2003

Materials Science and Engineering: C

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“…It should be stated that in the case of the LDA approximation, the ability to match the experimental interlayer spacing is due to a fortuitous cancellation of errors. 16 In contrast, calculations that are based on the generalized gradient approximation overestimate bond lengths and for the case of two graphene layers does not predict binding at all. 16 Using a density functional approach is also preferable to empirical approaches because it provides insight into the underlying physics in the system.…”

Section: Approachmentioning

confidence: 99%

“…16 In contrast, calculations that are based on the generalized gradient approximation overestimate bond lengths and for the case of two graphene layers does not predict binding at all. 16 Using a density functional approach is also preferable to empirical approaches because it provides insight into the underlying physics in the system. Previous studies have found that the weak van der Waals bonding has little impact on graphite properties once the proper spacing between layers is fixed for calculations.…”

Section: Approachmentioning

confidence: 99%

Ab initiostudy of polarizability and induced charge densities in multilayer graphene films

Stewart

Tiwari

2008

Phys. Rev. B

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We present an ab initio analysis of polarization of multilayer graphene systems under applied electric fields. The effects of applied electric fields are calculated using a Berry phase approach within a plane-wave density functional formalism. We have determined polarizability values for graphene films and carbon nanotubes and found that the polarizability of graphene films follows a linear relationship with the number of layers. We also examined changes in the induced charge distribution as a function of graphene layers. We focus, in particular, on the bilayer graphene system. Under applied electric fields, we found the Mexican hat band structure near the K point reported by previous groups. We found that the induced charge primarily accumulated on the B sublattice sites. This observation is supported by additional calculations with a tight-binding Green's function model. By examining the local density of states at the Fermi energy, we found a high density of states at the B sites at the Fermi energy. In contrast, coupling between A sites in neighboring graphene layers leads to negligible density of states at the Fermi level. This high density of states at the B sites results in greater induced charge under applied electric fields. This scenario of preferential induced charge on the B sublattice sites under applied electric fields could impact the stability of atoms and molecules absorbed on bilayer graphene.

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“…Not too surprisingly, one finds that values calculated from semiempirical or ab initio methods for the interlayer cohesive or exfoliation energy of graphite range from as little as 8 meV/atom up to 170 meV/atom. [1][2][3][4][5][6] Experimental determinations of the interlayer cohesive energy of graphite have been comparatively rare and are restricted to a heat of wetting experiment by Girifalco which yields an exfoliation energy of 43 meV/atom 7,8 and a measurement by Benedict et al based on radial deformations of multiwall carbon nanotubes which yields 35 meV/atom. 9 At this point it seems that not only the agreement between theory and experiment leaves room for improvement but that the experimental evidence for such comparisons should also be put on a firmer basis.…”

Section: Introductionmentioning

confidence: 99%

Interlayer cohesive energy of graphite from thermal desorption of polyaromatic hydrocarbons

2004

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We have studied the interaction of polyaromatic hydrocarbons ͑PAHs͒ with the basal plane of graphite using thermal desorption spectroscopy. Desorption kinetics of benzene, naphthalene, coronene, and ovalene at submonolayer coverages yield activation energies of 0.50 eV, 0.85 eV, 1.40 eV, and 2.1 eV, respectively. Benzene and naphthalene follow simple first order desorption kinetics while coronene and ovalene exhibit fractional order kinetics owing to the stability of two-dimensional adsorbate islands up to the desorption temperature. Preexponential frequency factors are found to be in the range 10 14 -10 21 s Ϫ1 as obtained from both FalconerMadix ͑isothermal desorption͒ analysis and Antoine's fit to vapor pressure data. The resulting binding energy per carbon atom of the PAH is 52Ϯ5 meV and can be identified with the interlayer cohesive energy of graphite. The resulting cleavage energy of graphite is 61Ϯ5 meV/atom, which is considerably larger than previously reported experimental values.

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Hard numbers on soft matter

Cited by 87 publications

References 30 publications

Van der Waals interactions of parallel and concentric nanotubes

Van der Waals interactions of parallel and concentric nanotubes

Ab initiostudy of polarizability and induced charge densities in multilayer graphene films

Interlayer cohesive energy of graphite from thermal desorption of polyaromatic hydrocarbons

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