Molecular Polarizability of Carbon Nanotube Models
Francisco Torrens
Institut Universitari de Ciència Molecular, Universitat de València
Dr. Moliner 50, E-46100 Burjassot (València), Spain
The interacting induced dipoles polarization model implemented in our program POLAR is used for the
calculation of the dipole-dipole polarizability  [1]. The method is tested with single-wall carbon
nanotube models as a function of nanotube radius and elliptical deformation [2-6]. The results for the
polarizability follow the same trend as reference calculations performed with our version of program
PAPID [7]. For the zigzag tubes, the polarizability is found to follow a remarkably simple law, i.e., varies
as the inverse of the radius. A dramatic effect is also found with elliptical deformation. It is found that the
polarizability and related properties can be modified continuously and reversibly by the external radial
deformation. The effects of curvature and radial deformation depend on the chirality of the tube. These
results suggest an interesting technology in which mechanical deformation can control chemical properties
of the carbon nanotubes. This remarkable and significant tunable adsorption can have important
implications for metal coverage and selective adsorption and desorption of foreign atoms and molecules
on nanotubes and can lead to a wide variety of technological applications, such as catalysts, hydrogen
storage, magnetic tubes, etc. Provisional conclusions follow. (1) It was shown that the polarizability of a
zigzag SWNT model could be modified reversibly and variably by the radial deformation. This novel
property may have important implications for various chemical and electronic applications, such as
selective adsorption and desorption of molecules. (2) The results of the present work clearly indicate that
due to the differences between POLAR and PAPID results, it may become necessary to recalibrate our
program POLAR. It appears that the results of good quality ab initio calculations might be suitable as
primary standards for such a calibration. Work is in progress on the recalibration of POLAR. (3) The
tunable polarizability reported in this paper can have important implications for metal coverage and
selective adsorption and desorption of foreign atoms and molecules on the carbon nanotubes. This could
allow the fine tuning of the properties of SWNTs via reversible deformation and ultimately lead to a wide
variety of technological applications such as variable and reversible quantum devices, catalysts, hydrogen
storage, chemical sensors, magnetic tubes, etc.
1
140
Molecular polarizability (Å 3 )
120

100
1276.932x 3
198.035x2
y=
+ 110.714 r = 0.999
+ 14.034x
 Ref.
80
60
y = 139.159x 3 - 48.928x2 + 3.961x +
33.741 r = 0.980
40
0
0.1
0.2
0.3
yy
Figure 1. Variation of the molecular polarizability of a 8,0 zigzag SWNT model as a function of the
elliptic radial deformation, yy.
[1]
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[2]
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[3]
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[4]
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[5]
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[6]
O. Gülseren, T. Yildirim and S. Ciraci, Phys. Rev. B 65 (2002) 153405.
[7]
F. Torrens, J. Phys. Org. Chem., in press.
2