Frequency-Dependent Polarizability of Boron Nitride Nanotubes:  A Theoretical Study

Abstract

In the present work, we have calculated the static and frequency-dependent polarizability tensors for a series of single-walled boron nitride nanotubes and compared them with corresponding results for carbon nanotubes. The calculations have been performed by employing a dipole-dipole interaction model based on classical electrostatics and an Unsöld dispersion formula. In comparison, we have carried out ab intio calculations at the SCF level of the static polarizability of the smaller nanotubes with the STO-3G basis set. For the frequencydependent polarizability of C 60 , we found excellent agreement among the most accurate SCF calculations in the literature, the interaction model, and experimental results. In particular, the frequency dependence is modeled accurately indicating that the interaction model is a useful tool for studying the frequency dependence of materials. For the nanotubes, we observe the same trends in the interaction model and in the SCF STO-3G results when the number of atoms is increased. However, the values obtained with the interaction model are about 100% larger than the corresponding SCF STO-3G results, due to the small size of the STO-3G basis set. We also find that the boron nitride nanotubes have smaller magnitudes of the polarizability tensor components than the corresponding components for the carbon nanotubes with the same geometry and number of atoms. Furthermore, we find that the geometry of the tube has a large influence on the anisotropy of the polarizability components, whereas the mean polarizability remains almost unaffected when the geometrical configuration is modified. Finally, we observe a relatively small frequency dependence of the polarizability tensor of BN nanotubes.

Size-scaling of the polarizability of tubular fullerenes investigated with time-dependent (current)-density-functional theory

“…[24] and the result from the pointdipole interaction (PDI) model of 522.9 a.u. [25]. All these values are in agreement with the experimental value of 516.2 ± 54 a.u.…”

“…(k = 1064 nm) [8]. For both the static and the frequency-dependent polarizability, the experimental results are in good agreement with recent quantum chemical calculations [23,24] and results from a frequency-dependent PDI model [25,32]. For C 70 an experimental value of 688 ± 94 a.u.…”

“…We compare our results with experimental data, with results obtained using wavefunction methods, and with results obtained using the PDI model [25,32]. Experimental results for the dipole-dipole polarizabilities of the C 60 and C 70 molecules have recently been obtained in the gas phase with the use of molecular beam experiments [7][8][9].…”

“…[24], and the PDI result of 522.6 a.u. [25]. Comparing the results from Table 1 Mean static dipole-dipole polarizability (in a.u.)…”

Ab initio calculations of optical properties of silver clusters: cross-over from molecular to nanoscale behavior

“…These involve tight-binding calculations [20][21][22], and the time-dependent density functional theory (TDDFT) approach [22]. A promising atomistic method that can be conveniently used on hundreds of atom systems is the capacitance-polarizability interaction model [23,24] which has been successfully used to study the effect of planar defects on the optical properties of Ag nanostructures [25]. Those based on the classical electrodynamic theory of a dielectric object in an electromagnetic field use methods such as the Mie theory [26,27], the discrete dipole approximation [28,29] and the finite-difference time-domain approaches.…”