The Static Polarizability and Second Hyperpolarizability of Fullerenes and Carbon Nanotubes † (original) (raw)
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Influence of defects in the carbon network on the static polarizability of fullerenes
Physics of the Solid State, 2009
The static polarizability of the C 60 , C 70 , C 80 , and C 186 fullerenes has been calculated within the semiempirical MNDO approximation implemented in the MOPAC quantum-chemical program package. It is demonstrated that the results obtained are comparable with experimental data and the results of the ab initio B3LYP method using the 6-31 G (d , p) basis set. The influence of topological defects (five-, seven-, and eightmembered rings), vacancies produced by removing pentagons, and nitrogen and boron atoms on the geometric parameters and the polarizability of the C 60 , C 240 , and C 540 fullerenes has been investigated by the MNDO method. It is revealed that the polarizability of the fullerene with topological defects is higher than the polarizability of the perfect icosahedral fullerene. The formation of vacancies in the carbon cage leads to a linear decrease in the polarizability of the fullerene and an increase in the specific polarizability. The polarizability of the heterofullerene with nitrogen or boron atoms spaced apart in the carbon cage is higher than that of the fullerene with heteroatoms located adjacent to each other.
Physical Review B, 2007
We present a model for the calculation of the polarization properties of fullerenes and carbon nanotubes. This model describes each atom by both a net electric charge and a dipole. Compared to dipole-only models, the consideration of electric charges enables one to account for the displacement of free electrons in structures subject to an external field. It also enables one to account for the accumulation of additional charges. By expressing the electrostatic interactions in terms of normalized propagators, the model achieves a better consistency as well as an improved stability. In its most elementary form, the model depends on a single adjustable parameter and provides an excellent agreement with other experimental and theoretical data. The technique is applied to a C 720 fullerene and to open and closed ͑5,5͒ nanotubes. The simulations demonstrate the improved stability of our algorithm. In addition, they quantify the role of free charges in the polarization of these structures. The paper finally investigates the field-enhancement properties of open and closed ͑5,5͒ nanotubes.
A charge-dipole model to compute the polarizability of fullerenes and carbonna notubes
Recent Progress in Computational Sciences and Engineering (2 vols), 2006
We present a model for the calculation of the polarization properties of fullerenes and carbon nanotubes. This model describes each atom by both a net electric charge and a dipole. Compared to dipole-only models, the consideration of electric charges enables one to account for the displacement of free electrons in structures subject to an external field. It also enables one to account for the accumulation of additional charges. By expressing the electrostatic interactions in terms of normalized propagators, the model achieves a better consistency as well as an improved stability. In its most elementary form, the model depends on a single parameter and provides an excellent agreement with other experimental/theoretical data. Compared to dipole-only models, the technique improves the calculation of the local fields. It also quantifies the role of free charges in the polarization of fullerenes and carbon nanotubes.
Nano Letters, 2003
An atomic dipole interaction model has been used for calculating the second hyperpolarizability of carbon nanotubes on a length scale up to 75 nm. It is demonstrated that an atomistic representation of mesoscale systems such as nanotubes can be used to obtain a cubic response property up to a size of the system where the property scales linearly with increasing size. In particular, it demonstrates that atomistic models are useful also for designing nonlinear molecular materials, where local modifications may give large macroscopic contributions. The saturation length has been calculated for carbon nanotubes. It is found that carbon nanotubes are comparable to conjugated polymers with respect to the magnitude of the second hyperpolarizability and are therefore very promising candidates for future nonlinear optical materials.
Static and dynamic polarizability of C540 fullerene
International Journal of Quantum Chemistry, 2012
State-of-the-art calculations of static and dynamic polarizabilities of the giant fullerene C 540 are presented. These density functional theory calculations have been performed using timedependent auxiliary density perturbation theory which was recently implemented in deMon2k (Carmona-Espíndola et al., JCP 2010, 133, 084102). For the polarizability calculations the local density approximation was used in combination with all-electron double-zeta valence polarization basis sets. To gain insight into the trend of these properties as the fullerene size increases the obtained results for C 540 are discussed with respect to those obtained for smaller fullerenes such as C 60 , C 70 , C 180 , and C 240. All fullerene structures were fully optimized without symmetry constrains. As the cluster size increases the dynamic polarizability strongly increases with respect to the static polarizability. Our analysis shows that static and dynamic polarizabilities per atom increase significantly with fullerene size. Moreover, the increase in the dynamic polarizabilities per atom is larger than for the static ones. V
Journal of Molecular Structure: THEOCHEM, 1998
The static third-order polarizabilities (g) of C 60 , C 70 , five isomers of C 78 and two isomers of C 84 were analyzed in terms of three properties, from a geometric point of view: symmetry; aromaticity; and size. The polarizability values were based on the finite field approximation using a semiempirical Hamiltonian (AM1) and applied to molecular structures obtained from density functional theory calculations. Symmetry was characterized by the molecular group order. The selection of six-member rings as aromatic was determined from an analysis of bond lengths. Maximum interatomic distance and surface area were the parameters considered with respect to size. Based on triple linear regression analysis, it was found that the static linear polarizability (a ) and g in these molecules respond differently to geometrical properties: a depends almost exclusively on surface area while g is affected by a combination of number of aromatic rings, length and group order, in decreasing importance. In the case of a, valence electron contributions provide the same information as all-electron estimates. For g, the best correlation coefficients are obtained when all-electron estimates are used and when the dependent parameter is ln(g) instead of g. Published by Elsevier Science B.V. Journal of Molecular Structure (Theochem) 454 (1998) 135-148 THEOCH 5750 0166-1280/98/$ -see front matter Published by Elsevier Science B.V.
Polarizability of C70 Fullerene Derivatives C70X8 and C70X10
Fullerenes Nanotubes and Carbon Nanostructures, 2012
The mean polarizabilities and their anisotropies for C70 derivalives C70X8 and C70X10 (X = H, Me, Ph, Cl, Br, OOt Bu) have been calculated. The deviation from additive scheme, that is, depression of polarizability, has been found for all studied C70X8 and C70X10 molecules. The deviation increases as the number of added X groups increases. The correction to additive polarizability taking into account this phenomenon is considered and can be used in the design of modern fullerene-containing materials.
Effect of size and deformation on polarizabilities of carbon nanotubes from atomic increments
Future Generation Computer Systems, 2004
The interacting induced-dipole polarization model implemented in program POLAR is used for the calculation of the polarizability α. The method is tested with single-wall carbon nanotubes (SWNTs) as a function of radius and elliptical deformation. This work gives a partial success with the application of POLAR when compared with reference calculations performed with program PAPID. α follows a simple law. PAPID differentiates more effectively than POLAR among SWNTs with increasing radial deformation. α can be modified reversibly by external radial deformation. Different effective α eff are calculated for the atoms at the highest and lowest curvature sites. The difference between POLAR and PAPID is due to the different parameterization scheme used for the initial atomic polarizabilities.
The Journal of Physical Chemistry B, 2004
The dipole-dipole polarizability, R, and the second hyperpolarizability, γ, as well as the corresponding linear and third-order susceptibilities, (1) and , have been calculated for C 60 fullerene clusters by a point-dipole interaction (PDI) model. The size dependences of a linear chain, a monolayer film, and a face-centered cubic crystal cluster have been investigated. It is found that the effects of the surrounding molecules on the molecular R and γ are large, in particular for the chain and the film because of the anisotropic surroundings, and that large clusters are required to obtain converged results. A localized PDI model gives the opportunity to divide R and γ into fragment contributions, and it is found that R and γ of molecules in the middle of the chain converge slower than the properties for the end molecules with respect to the length of the chain. Similar results are found for the monolayer film. Finally, and have been calculated by using a modified local-field theory including the induced dipole moments of the surrounding molecules explicitly. The corresponding refractive index and dielectric constant compare well with experiments. On the other hand, the comparison of (3) with experiments is complicated by dispersion and vibrational contributions. Nonetheless, our value of (3) is in good agreement with a recent quantum chemical calculation adopting a self-consistent reaction-field model. † Rijksuniversiteit Groningen.