Self-consistent field calculations of interaction energies were taken by centering the frame over the pillar then lowering it incrementally until the frame reached covalent-bonding distance from the pillar’s step edges. Energetics of Nanoframe Positioned along CNT Pillar (e) through (h): Candidate models for the rhodium nanoframe. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. (a) through (d): TEM images of the etched rhodium nanoframes. None of these models were stable, however, and it was found that frames derived from a simple cubic structure relaxed to a shape closely resembling the dimensions of those seen in the TEM images. Originally, models were constructed using structures derived from face-centered cubic facets, since this is where rhodium is deposited experimentally before corrosion etching (from a bromide-ion–coated palladium cube with only said facets exposed). The slight concavity and bulbous edges of the rhodium frames were the primary characteristics we attempted to re-create. (c) (12,0) pillar model as seen from above. (b) TEM image of the NGP base region, seen from below through a SiO2 substrate. (a) A (12,0) carbon nanotube–graphene pillar. 7 Though all the TEM images of the tube diameters matched a zigzag (M,0) chirality, conductive (3*x,0) and semiconductive (3*x͡,0) chiralites showed a marked difference in response to uniaxial bending in classical MD simulations of a 0.1 ns duration.Ĭarbon Nanotube–Graphene Pillars. When relaxed with SIESTA, the junction area steps were found to have an interlayer structure resembling the sp3 bonding seen with adatom-covered graphite surfaces. 2 These included step height distance in the tube–graphene interface region, chiralities of the tubes, and the structure of the truncated outer “sheath”. Several factors were considered in re-creating Zhu’s experimental results. A transparent grey isosurface is shown for an electron density of ? = 0.031 eV/?. The frame–pillar system at 3 ? separation. The density functional theory ( DFT) package SIESTA 6 was used for additional relaxations and calculating the combined frame–pillar system energies along several z-displacement points. Modeling and stability testing was performed in Quantumwise’s ATK 3 using the REBO 4 and EMT 5 force fields for the pillars and frames, respectively. These models were used to test whether a combination of the two systems would lead to physisorbtion. As part of his applied project for his Professional Science Master’s in Nanoscience at ASU, Ben Folsom constructed theoretical models for recently synthesized hollowed rhodium nanoframes 1 and covalently bonded carbon nanotube–graphene pillars 2 based on the TEM images provided in the source publications.
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