The fabrication of graphene nanoribbons from carbon nanotubes (CNTs) treated with potassium permanganate in a concentrated sulfuric acid solution has been reported by Kosynkin et al. [Nature (London) 458, 872 (2009)]. Here we report ab initio density functional theory calculations of such unzipping process. We find that the unzipping starts with the potassium permanganate attacking one of the internal C–C bonds of the CNT, stretching and breaking it. The created defect weakens neighboring bonds along the length of the CNT, making them energetically prone to be attacked too.

We report three types of nonplanar conformations, ␣, ␤, and ␥, for a neutral isolated oligoaniline molecule as well as for an oligoaniline with Au and Pd atoms attached at its ends. Each type of conformation has several conformers of nearly equal energies. An applied external voltage can be used to switch between conformations, producing in the process a sharp decrease of their energies. These bias voltage-induced conformational changes are a potential switching mechanism for two terminal molecular devices at the nanoscale domain. They cause the conductivity of the molecule to alternate between high and low states, compensating for the behavior of typical three-terminal devices, needed for the development of a gate-less electronics.

We demonstrate the switchability of the molecular conductivity of a citrate. This was made possible through mechanical stretching of two conformers of such citrate capped on and linked between gold nanoparticles (AuNPs) self-assembled as a film. On the basis of experimental results, theoretical analysis was conducted using the density function theory and Green's function to study the electron flux in the backbone. We found that the molecular conductivity depended on the pathways of electrons that were controlled by the applied mechanical stress. Under stress, we could tune the conductivity up and down for as much as 10-fold. The mechanochemistry behind this phenomenon is an alternative branch of chemistry.

We extend the Mayadas and Shatkes's approach ͓Phys. Rev. B 1, 1382 ͑1970͔͒ to study the optical properties of polycrystalline metal thick films in the visible and far infrared range of the spectrum. We show that in this range grain boundary scattering can account for the experimentally observed lowering of the film reflectivity as the mean size of its constituent grains decreases.

We develop an ab initio procedure for materials participating in electron transfer reactions, to consider biatomic backgrounds (e.g., substrates, catalysts, electrodes), thus the precise effects of the continuum and long-range interactions as well as the effects of the discrete and local nature of the chemistry can be combined to study molecules under such biatomic backgrounds. We test this new procedure by studying the reactivity of molecular oxygen on bimetallic clusters of platinum and cobalt. The reaction of molecular oxygen on the surface of the L1(2) phase of Co(3)Pt yields three distinct chemisorbed precursors, two of which are energetically almost degenerate. One precursor is formed across a bridge site with the molecule parallel to the surface, the second one is formed at the bridge with the molecule again parallel to the surface, and the third is formed in the threefold fcc hollow site, with the molecule slightly tilted in a top-hollow-bridge geometry.