1,720,985 research outputs found
Nanotubes and Peapods
No full textThe author report an updated review of the recent progress in the characterization of inorganic nanotubes and in the chemistry of tubular structures carried out by theoretical investigations, based on DFT methods, with particular emphasis devoted to the description of the novel hybrid nanopeapod structures
A Pyracylene Model for the Interaction of Transition Metal Complexes: A Density Functional Study
No full textA Density Functional Study on the Interaction of a Polycyclic Aromatic Molecule and the Silicon (001) Surface
No full textStatic and dynamical density functional theory calculations have been carried out to investigate the coordination and haptotropic rearrangement of the Cr(CO)(3) fragment on the (6,0) carbon nanotube sidewalls. Geometry optimizations have been performed on the Cr(CO)(3)-(C72H12) complex, pointing out the preferred coordination sites of the metal fragment on the nanotube sidewalls. We find a hole site configuration of the Cr(CO)(3) to be the global energy minimum of the Cr(CO)(3)-(C72H12) system, with a binding energy of 143 kJ mol(-1). The shifting of the Cr(CO)(3) complex between two coordination sites on adjacent hexagonal rings of (6,0) carbon nanotubes has been investigated by means of Car-Parrinello simulations, from which the transition state structure for the haptrotropic rearrangement has been localized and found to be 68 kJ mol(-1) above the global minimum structure
Selective functionalization of the Si(100) surface by a bi-functional alkynilamine molecule: a density functional study of the switching adsorption linkage
No full textThe reaction of the bifunctional organic molecule 1-dimethylamino-2-propyne (DMAP) on the Si(100) surface has been investigated by density functional calculations on a one-dimer cluster model. We found that, once in the physisorbed dative bonded well (-22.1 kcal mol(-1)), DMAP can proceed to react via a number of pathways. We first considered the cycloaddition of the C equivalent to C triple bond, leading to Si-C di-sigma bonded product (-58.6 kcal mol(-1)), computing an energy barrier of 33.1 kcal mol(-1). We considered also possible dissociative pathways of dative bonded DMAP, i.e., methylene C-H, methyl C-H or N-CH3 bond cleavage
DFT Investigations of Formic Acid Adsorption on Single-Wall TiO<sub>2</sub> Nanotubes: Effect of the Surface Curvature
No full textWe carried out a theoretical study based on DFT calculations to provide a detailed characterization of the structural, electronic, and adsorption properties of single-walled TiO2 anatase nanotubes. We nanotube models of increasing diameter, formally obtained by rolling a TiO2 anatase monolayer around the [(1) over bar 01] and [010] directions, giving rise to (n,0) and (0,m) nanotubes, respectively. We considered finite cluster models for both (n,0) and (m,0) TiO2 nanotubes, with diameters ranging from 5 to 30 angstrom, thus' approaching realistic nanotube dimensions. Our results show that (n,0) tubes are lower in energy with respect to (0,m) tubes. For (n,0) tubes with diameters greater than 23 angstrom, the electronic energy and the band gap are almost converged with respect to the diameter length. We then investigated the adsorption of formic acid on the TiO2 nanotube sidewalls, as the simplest model of photosensitizers binding to the TiO2 surface, relevant to dye-sensitized solar cells. Adsorption of formic acid was investigated on (12,0) and (0,4) TiO2 nanotubes, optimizing two monodentate modes and one bidentate adsorption mode, and comparing the results to those obtained for a planar TiO2 surface. We find that while for a planar surface a bridged bidentate configuration is the more stable, the effect of the curvature in TiO2 nanotubes leads a monodentate configuration to be the more stable structure. These results are interpreted in terms of the peculiar electronic properties of TiO2 nanotubes and their implications for use of nanotubes in dye-sensitized solar cells are discussed
The coordination chemistry of carbon nanotubes: a density functional study through a cluster model approach
No full textA density functional study of (PH3)2M(eta2-C2X4) alkene complexes for the group 10 metals Ni, Pd, Pt: the effect of electron-attracting substituents
No full textA density study of [M(PH3)2(n2-C2X4)] alkene complexes for the Group 10 metals Ni,Pd,Pt: the effect of electron-attracting substituents
No full text- …
