Linear-scaling density functional theory simulations of polar semiconductor nanorods

Hine, Nicholas D. M.; Avraam, Philip; Tangney, Paul; Haynes, Peter

doi:10.1088/1742-6596/367/1/012002

Cited by 16 publications

(25 citation statements)

References 38 publications

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“…This is confirmed in Fig. 5, which compares the density of states of a 16 unit cell (10, 0) semiconductor CNT and a water molecule when mutually isolated, and the corresponding CNT/water local density of states (LDOS) 49 with the water adsorbed. Indeed, the LDOS/DOS of the CNT are indistinguishable.…”

Section: Considerations Of the Electronic Energy Level Alignmentsupporting

confidence: 54%

Does water dope carbon nanotubes?

Bell¹,

Payne²,

Mostofi

2014

The Journal of Chemical Physics

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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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Section: Considerations Of the Electronic Energy Level Alignmentsupporting

confidence: 54%

Does water dope carbon nanotubes?

Bell¹,

Payne²,

Mostofi

2014

The Journal of Chemical Physics

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“…This is confirmed in Fig. 8.8, which compares the density of states of a 16 unit cell (10, 0) semiconductor CNT and a water molecule when mutually isolated, and the corresponding CNT/water local density of states 3 (LDOS) [34] with the water adsorbed. Indeed, the LDOS/DOS of the CNT are indistinguishable.…”

Section: Considerations Of the Electronic Energy Level Alignmentsupporting

confidence: 52%

Charge Doping in Water-Adsorbed Carbon Nanotubes

Bell

2015

Springer Theses

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In the previous chapters, we have largely focused on the role of transmission between CNTs and its effect on the conductance of the network as a whole. In this chapter we investigate a separate mechanism, that of charge doping due to adsorbed water molecules, and consider its effect on the conductivity of individual CNTs.The effect of water on the electrical properties of carbon nanotubes (CNTs) has been controversial for some time. Theoretical calculations have suggested that water dopes CNTs, predicting a strong dependence of CNT conductivity on humidity. The theoretical evidence for doping in this system has been questioned, however, and experimental studies have not been able to clearly confirm or refute this model. In this chapter, we propose that the theoretical methods used in previous calculations are indeed insufficient. We investigate in detail the conditions that must be satisfied for charge doping to occur, and provide a theoretical method, based on large-scale density functional theory calculations, to identify the presence of charge doping. Key to our analysis is the isolation of electrostatic effects, which we do using a novel application of maximally-localised Wannier functions. Our findings lead us to conclude that water does not dope CNTs.Parts of this chapter have been published [1].

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“…Their overall stoichiometry and number of atoms is reported in Table 2. To prevent the occurrence of large longitudinal polarisations 99 which may affect the geometry optimisation of the systems, all the finite NTs model were symmetric with respect to a plane containing the innermost Si-ring (Ring 0 in Fig. 8).…”

Section: Optimisation Of the Nt Cb And Band Gapmentioning

confidence: 99%

Large-scale density functional theory simulation of inorganic nanotubes: a case study on Imogolite nanotubes

Poli

Elliott

Hine

et al. 2015

Materials Research Innovations

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The high experimental control over inorganic Imogolite-like open-ended nanotubes (Imo-NTs) composition, dimensions and monodispersity together with the potentially huge range of tuneable properties that can be introduced by chemical functionalisation and doping make Imo-NTs appealing substrates for nanotechnology, as artificial ion-channels and in chemical separation. Investigation of Imo-NTs electronic and spectroscopic properties has so far been hampered by the large size of the systems repeat unit (+300 atoms), which pose severe challenges and accuracy-viability compromises for standard plane-wave (fixed atomic basis set) density functional theory (DFT) simulations. These challenges can, however, be met by linear-scaling DFT (LS-DFT) approaches based on in situ optimisation of minimal basis sets. Here, we illustrate the applicability of LS-DFT to Imo-NTs by providing structural and electronic characterisation of periodic and finite models of aluminosilicate (AlSi) and methylated-AlSi Imo-NTs. It is shown that adoption of moderate kinetic energy cutoff (1000 eV) and basis set truncation radius (8 Bohr) leads to optimal accuracy-viability compromised for geometrical optimisation of Imo-NTs. These results should be useful for future LS-DFT investigation of Imo-NTs and other AlSi-based functional materials.

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Linear-scaling density functional theory simulations of polar semiconductor nanorods

Cited by 16 publications

References 38 publications

Does water dope carbon nanotubes?

Does water dope carbon nanotubes?

Charge Doping in Water-Adsorbed Carbon Nanotubes

Large-scale density functional theory simulation of inorganic nanotubes: a case study on Imogolite nanotubes

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