We calculate the long-range perturbation to the electronic charge density of carbon nanotubes (CNTs) as a result of the physisorption of a water molecule. We find that the dominant effect is a charge redistribution in the CNT due to polarisation caused by the dipole moment of the water molecule. The charge redistribution is found to occur over a length-scale greater than 30 Å, highlighting the need for large-scale simulations. By comparing our fully first-principles calculations to ones in which the perturbation due to a water molecule is treated using a classical electrostatic model, we estimate that the charge transfer between CNT and water is negligible (no more than 10−4 e per water molecule). We therefore conclude that water does not significantly dope CNTs, a conclusion that is consistent with the poor alignment of the relevant energy levels of the water molecule and CNT. Previous calculations that suggest water n-dopes CNTs are likely due to the misinterpretation of Mulliken charge partitioning in small supercells.
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Research Article| October 27 2014
Does water dope carbon nanotubes?
Robert A. Bell;
Michael C. Payne;
Robert A. Bell, Michael C. Payne, Arash A. Mostofi; Does water dope carbon nanotubes?. J. Chem. Phys. 28 October 2014; 141 (16): 164703. https://doi.org/10.1063/1.4898712
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