Modeling adsorbate‐induced property changes of carbon nanotubes

Abstract

Because of their potential for chemical functionalization, carbon nanotubes (CNTs) are promising candidates for the development of devices such as nanoscale sensors or transistors with novel gating mechanisms. However, the mechanisms underlying the property changes due to functionalization of CNTs still remain subject to debate. Our goal is to reliably model one possible mechanism for such chemical gating: adsorption directly on the nanotubes. Within a Kohn-Sham density functional theory framework, such systems would ideally be described using periodic boundary conditions. Truncating the tube and saturating the edges in practice often offers a broader selection of approximate exchange-correlation functionals and analysis methods. By comparing the two approaches systematically for NH and NO adsorbates on semiconducting and metallic CNTs, we find that while structural properties are less sensitive to the details of the model, local properties of the adsorbate may be as sensitive to truncation as they are to the choice of exchange-correlation functional, and are similarly challenging to compute as adsorption energies. This suggests that these adsorbate effects are nonlocal. © 2017 Wiley Periodicals, Inc.

Carbon Nanotube Chemical Sensors

“…Clar demonstrated that the valence bond structure with the most aromatic sextets best models the reactivity of polyaromatic hydrocarbons and that structures possessing only aromatic sextets are especially stable, Figure . It has been shown that structures with the maximum amount of aromatic sextets for a given chirality and number of carbon atoms best describe the reactivity and geometry of CNTs and CNT–reactant studies. − Accordingly, computational investigations employing “straight cut” CNT samples might misrepresent the reactivity of the studied model, which might be the source of some inconsistencies in published results on CNT–analyte interactions. For detailed discussions on the Clar sextet rule in CNTs, we refer the interested reader to key studies by Matsuo et al, Baldoni et al, , and Ormsby et al , …”

Local Decomposition of Hybridization Functions: Chemical Insight into Correlated Molecular Adsorbates

“…It can be advantageous to truncate a surface for studying the properties of adsorbates [70][71][72][73][74][75][76], or for simulating the electron transport properties through molecules in a molecularjunction setup [77][78][79][80][81]. This is called a (truncated) cluster approach in this work.…”