We have evaluated the energies required to twist carbon nanotubes (NTs), and investigated effects of these distortions on their electronic structure electrical properties. The computed distortion are high, indicating that it is unlikely extensive twisting result thermal excitation. Twisting strongly affects NTs. Normally metallic armchair $(n,n)$ NTs develop a band-gap which initially scales linearly with angle then reaches constant value. This saturation associated structural transition...

We have modeled the adsorption of various substituted derivatives benzene on a graphene sheet, using first-principles density functional theory−local approximation method. The presence groups can significantly alter overall magnitude π−π interactions between adsorbed molecules and by giving rise to strong medium-range involving π-orbitals substituents. When substituents simultaneously permit formation hydrogen bonds molecules, it is possible evaluate relative contributions bonding π-based...

The electronic structure of finite-length armchair carbon nanotubes has been studied using several ab-initio and semiempirical quantum computational techniques. additional confinement the electrons along tube axis leads to opening a band-gap in short tubes. value decreases with increasing length; however, decrease is not monotonic but shows well-defined oscillation This can be explained terms periodic changes bonding characteristics HOMO LUMO orbitals Finite-size graphene sheets are also...

Grafting isophthalic acid groups to linear connectors produces tetracarboxylic acids 2−4, which are extended analogues of trimesic (1). Normal pairwise association -COOH induces form a hexagonal network held together by six hydrogen bonds per molecule. In contrast, 2−4 designed two polymorphs, parallel II and Kagomé III, linked eight The particular connectivity these networks allows smooth transition from one the other without introducing discontinuities in bonding. DFT calculations suggest...

DFT calculations reveal that aminotriazines have a strong affinity for graphite and suggest part of the driving force adsorption is specific attractive interaction NR2 groups with underlying surface.

A new azobenzene-thiophene molecular switch is designed, synthesized, and used to form self-assembled monolayers (SAM) on gold. An "on/off" conductance ratio up 7 x 10(3) (with an average value of 1.5 10(3)) reported. The "on" state clearly identified the cis isomer azobenzene moiety. high on/off explained in terms photoinduced, configuration-related changes electrode-molecule interface energetics (changes energy position orbitals with respect Fermi electrodes) addition tunnel barrier length...

Single tetracyanoethyelene (TCNE) molecules on Cu(111) are reversibly switched among five states by applying voltage pulses with the tip of a scanning tunneling microscope. A pronounced Kondo resonance in spectroscopy indicates that one is magnetic. Side bands appear at energies which correspond to inter- and intramolecular vibrational modes. Density functional theory suggests molecular deformation changes occupancy TCNE's orbitals, thus producing magnetic state.

The adsorption of trimesic acid (TMA) on a graphene surface has been studied with density functional theory. By considering the single TMA molecule different sites graphene, we have able to perform detailed analysis equilibrium geometry, charge transfer, electronic properties in terms states and band structure, finally scanning tunneling microscopy simulations those simple systems. results for isolated were then compared behavior unit within two self-assembled monolayers. Our indicate that...

Flat bands in Kagome graphene might host strong electron correlations and frustrated magnetism upon electronic doping. However, the porous nature of opens a semiconducting gap due to quantum confinement, preventing its fine-tuning by electrostatic gates. Here we induce zero-energy states into inserting π-radicals at selected locations. We utilize on-surface reaction tribromotrioxoazatriangulene molecules synthesize carbonyl-functionalized on Au(111), thereafter modified situ exposure atomic...

The adsorption of CO2 in MOF‐808, NU‐1000 and a series rare‐earth CU‐10 analogues has been studied with first principles DFT classical Monte‐Carlo methods. calculations describe the interaction different metal‐organic frameworks (MOFs) as physisorption, but where we can distinguish several sites vicinity metal nodes. Beyond identification sites, MOFs were synthesized, activated, characterized to evaluate their experimental N2 capacity. Classical Grand Canonical (GCMC) simulations for are...

We theoretically studied the electronic and electrical properties of metallic semiconducting peapods with encapsulated C_{60} (C_{60}@CNT) as a function carbon nanotube (CNT) diameter. For exothermic (CNT diameter > 11.8 A), only minor changes, ascribed to small structural deformation walls, were observed. These include electron charge transfer (less than 0.10 electron) from CNT molecules poor mixing orbitals those CNT. Decreasing leads modest increase density located between C_{60}'s. More...

First-principles density-functional theory (DFT) method has been used to investigate the structural and electronic properties of regioregular head-to-tail poly(3-hexylthiophene-2,5-diyl) (rrP3HT) crystal. Among different configurations investigated for rrP3HT crystal, most stable is a staggered structure which 875 meV/monomer more than isolated chains. Electronic crystal are strongly influenced by magnitude $\ensuremath{\pi}\text{\ensuremath{-}}\ensuremath{\pi}$ interactions that can be...

Two-dimensional supramolecular multicomponent networks on surfaces are of major interest for the building highly ordered functional materials with nanometer-sized features especially designed applications in nanoelectronics, energy storage, sensors, etc. If such molecular edifices have been previously built noble metals or HOPG surfaces, we successfully realized a 2D open framework silicon adatom-based surface under ultrahigh vacuum thermal stability up to 400 K by combining...

The interaction of the strong electron-acceptor tetracyanoethylene (TCNE) with Cu(100) surface has been studied scanning tunneling microscopy experiments and first-principles density functional theory calculations. We compare two different adsorption models experimental results show that molecular self-assembly is caused by a structural modification rather than formation coordination network diffusing Cu adatoms. Surface atoms become highly buckled chemisorption TCNE accompanied partial...

The bonding of CO and NO to the dimers Pd2, Cu2, PdCu was studied with quantum chemical linear combination Gaussian-type orbitals-model core potential-density functional (LCGTO-MCP-DF) method. Bonding occurs preferably at bridge site on Pd2 end-on Cu2. On PdCu, binds in a or a-top geometry Pd, while fashion. binding energy Pd (Cu) atom is slightly smaller (larger) than that for homonuclear dimer (Cu2). These trends are line propensity back-donation various metal dimers. complexes determined...

We calculated the effect of varying length a metal-semiconductor carbon nanotube junction on its electrical properties. Joining metallic (5,5) tube to semiconducting (10,0) leads creation new states near Fermi energy and produces larger conductance gap (about 2 eV) than band segment 1 eV). The reflect charge transfer from segment. is due mismatch in conducting segments. Although number vicinity EF increases significantly with increasing length, behavior does not acquire characteristics...

We investigate theoretically the switching characteristics of semiconducting carbon nanotubes connected to gold electrodes under an external (gate) electric field. find that introduction holes is necessary account for experimental observations. identify metal-induced gap states (MIGS) at contacts and MIGS undoped tube would not significantly affect behavior, even very short lengths. also explore miniaturization limits nanotube transistors, and, on basis their ratio, we conclude transistors...

We studied the influence of π-orbital coupling in a 1D stack 4,4'-biphenyldithiol (BDT) on resulting electronic and electrical properties assembly. The conduction field-switching BDT assembly are compared as intermolecular distances reduced to below 4 Å. system regime strong π-interactions shows large conductance modulations upon application transverse gate field. switching mechanism involves delocalized π-resonance, i.e., resonant tunneling π- π*-bands transmission is found be significantly...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemisorption and diffusion of atomic hydrogen in on cluster models palladium, rhodium bimetallic palladium tin, zinc catalystsAlain Rochefort, Jan Andzelm, Nino Russo, Dennis R. SalahubCite this: J. Am. Chem. Soc. 1990, 112, 23, 8239–8247Publication Date (Print):November 1, 1990Publication History Published online1 May 2002Published inissue 1 November...

We report a detailed investigation of the self-assembly organic semiconductor rubrene on low-index (100) and (110) facets copper by scanning tunneling microscopy (STM) supported density functional theory (DFT) calculations. Rubrene adsorbs in orientations depending substrate symmetry, resulting different self-assembled motifs. STM images point to an asymmetric adsorption geometry, DFT calculations further suggest that molecule twisted conformation.

Density functional theory/time-dependent density theory (DFT/TD-DFT) calculations were performed to investigate the structural, electronic, and optical properties of ionic Ir complexes with several different substituents on cyclometalated ligand. Geometric parameters, highest occupied molecular orbital−lowest unoccupied orbital (HOMO−LUMO) energy gap, Mulliken charge parts molecule obtained correlated calculated emission absorption energies. We also discuss influence position...