The initial oxidation stages of perfect and defective graphitic surfaces exposed to atomic oxygen have been studied with a combined high-resolution photoemission spectroscopy (HR-PES) density functional theory (DFT) computational approach. resulting oxygen-containing surface groups are identified by analyzing the multicomponent C 1s O core level spectra that then interpreted on basis DFT calculations. In stage, epoxy formed graphene, whereas preferential adsorption atoms vacancies results in...

The differences in the electroluminescence (EL) of red‐emitting free‐base ( H2TPP ) and Zn‐metalated ZnTPP archetypal porphyrins are rationalized light‐emitting electrochemical cells by means an electric‐field dependent effect, leading to whitish reddish devices, respectively. Although shows superior photophysical features compared , devices prepared with surprisingly stand out a deep‐red EL similar its photoluminescence (PL), while feature unexpected EL. Standard arguments such as...

The optical properties of the flavylium state cyanin dye are simulated numerically by combining Car–Parrinello molecular dynamics and linear-response time-dependent density functional theory calculations. spectrum calculated in gas phase is characterized two peaks yellow blue (green violet), using a GGA-PBE (hybrid-B3LYP) DFT functional, which would bring about greenish (bright orange) color incompatible with dark purple hue observed nature. Describing effect water solvent through...

Research for third generation solar cell technology has been driven by the need to overcome efficiency and cost problems encountered current crystalline Si- thin-film-based cells. Using first-principles methods, Ge/Si Si/Ge core/shell Si-Ge layered nanowires are shown possess required qualities an efficient use in photovoltaic applications. We investigate details of their band structure, effective mass, absorption property, charge-carrier localization. The strong charge separation improved...

The recursion method of Haydock, Heine and Kelly is a powerful tool for calculating diagonal matrix elements the resolvent quantum-mechanical Hamiltonian operators by elegantly expressing them in terms continued fractions. In this paper we extend to off-diagonal general (possibly non-Hermitian) apply it simulation molecular optical absorption photoemission spectra within time-dependent density-functional many-body perturbation theories, respectively. This demonstrated with couple...

An important pathway for functionalization of porphyrin-based organic-inorganic structures is the metalation porphyrins. Recently, porphyrin was demonstrated on different metal oxide surfaces, however, underlying mechanisms regarding role surface morphology, substituted metal, and ligands are still under investigation. Here we address adsorption self-metalation H2TPP a MgO(001) with low-coordinated sites. We employ ab initio molecular dynamics simulations around room temperature to provide...

The electronic structure of Mg and free-base tetraphenylporphyrin films on Ag(100) is investigated by one- two-photon photoemission in combination with calculations using density functional theory the self-consistent $G{W}_{0}$ method. We determine two highest occupied nearly degenerate lowest unoccupied molecular orbitals. Higher states are seen an enhanced emission as a final-state effect. For photon energies close to prominent absorption Soret band we observe strong electron attributed...

Diffuse insterstellar bands (DIBs) are absorption features in the spectra of reddened stars, caused by light interstellar medium. Organic molecules based on polycyclic aromatic hydrocarbons (PAHs), revealed infrared emission bands, present medium and considered to be possibly responsible for DIBs. However, specific carbon-based nanostructures still unidentified, with notable exception C 60 + (Campbell et al. 2015, Nature, 523, 322). In work, using state-of-the-art time-dependent density...

The formation of carbon nanorods from various types nanotubes has been investigated by performing molecular-dynamics computer simulations. Calculations have realized using an empirical many-body potential energy function for carbon. It found that nanorod formed with different chirality is not stable even at low temperature.

Abstract The structural stability of carbon nanotori have been investigated by performing molecular‐dynamics simulations. systems considered are C170, C250, C360, C520 and C750 tori, which constructed using a recently developed algorithm based on the idea Fonseca et al. Calculations, realized an empirical many‐body potential energy function for carbon. It has found that all stable under heat treatment.

Thin porphyrin films as employed in modern optical devices or photovoltaic applications show deviating electronic and properties from the gasphase species. Any understanding of physical origin may pave way to a specific engineering these via ligand substituent control. Here we investigate impact crystallization prototypical porphyrins on levels framework density functional theory many-body perturbation theory. Crystallization substantially shrinks HOMO-LUMO gap based polarization effects. We...

On page 6737, M. Bockstedte, R. D. Costa, and co-workers describe whitish light-emitting electrochemical cells based on red fluorescent free base porphyrins. An electric field effect that induces the presence of high- low-energy emitting regioisomers, in which inner ring H atoms are placed vicinal collinear configurations, respectively, causes white emission.

The effect of chirality on the structural stability single-wall carbon nanotubes have been investigated by performing molecular-dynamics computer simulations. Calculations realized using an empirical many-body potential energy function for carbon. It has found that nanotube in chiral structure is more stable under heat treatment relative to zigzag and armchair models. diameter tubes slightly enlarged treatment.

The structural properties of carbon nanorods obtained from diamond crystal have been investigated by performing molecular-dynamics computer simulations. Calculations realized using an empirical many-body potential energy function for carbon. Diamond generated three low-index planes crystal. It has found that the average coordination number, cross-section geometry, and surface orientation which nanorod is play a role in stability under heat treatment. most stable (111) surface.

Alterations in the electronic transport properties of C(4,4) single walled carbon nanotube when an agent is introduced to outer surface are investigated theoretically. Several chemical agents this context investigated. The calculations performed two steps: First optimized geometry for functionalized obtained using semi-empirical at PM3 level, and then relations non equilibrium green-function approach. Gaussian Transiesta-C simulation packages used correspondingly. "electrodes" chosen be...

The adsorption of Co-tetraphenylporphyrin at relevant low-coordinated sites on MgO(100) shows distinct features from terrace-site and multilayer films in the near-valence corelevel regions electronic structure.

Changes in the optical response of a CdTe quantum dot (QD) due to dynamic and surface effects are investigated using ab initio methods. The model successfully captures experimentally reported non‐linear trends spectra. combination molecular dynamics, time‐dependent DFT, spectroscopy provides very effective method investigate various on small QDs, explore generalizable for similar structures.