Ping Peng

Origins of high visible light transparency and solar heat-shielding performance in LaB6

We investigated the optical properties of LaB6 using first-principles calculations within the framework of density functional theory. It was found that our calculated results are in excellent agreement with the previously reported available and experimental findings. Analysis of the dielectric functions showed that LaB6 has the unique optical behavior in the visible and near infrared range and revealed that origins of solar heat-shielding performance and high visible transparency for LaB6 should be ascribed to its plasmonic behaviors.

Effects of nitrogen in Stone-Wales defect on the electronic transport of carbon nanotube

The effects of nitrogen substitutional doping in Stone-Wales (SW) defect on the transport properties of single-walled nanotubes are simulated by using density functional theory and nonequilibrium Green’s functions. It is found that the nitrogen in SW produces half-filled band near the Fermi level in which the electron effective mass varies with the changing of the position of nitrogen. The total transmission coefficients nearby the Fermi level increase and the others decrease after doping. The nitrogen doping and SW defect enhance the transport property of semiconducting (8, 0) and weaken that of quasimetallic (9, 0).

Curvature effects on electronic properties of small radius nanotube

The authors use the density functional theory associated with nonequilibrium Green function to calculate (2,2) and (3,3) single-walled nanotubes. The result of T(E) imply that π or π* band has been suppressed at certain electronic energy region result in the effect of curvature induce complex hybridization procedure. In view of the I-V characteristics of (2,2) tube, it is found that the current curve appears to have an oscillation behavior. These peculiar electronic transport properties of small diameter tube directly relate to a large curvature effect, which may be useful for the manufacture of electronic applications.

Site preference of Re in NiAl and valence band structure of NiAl containing Re: First-principles study and photoelectron spectrum

The site preference of Re in NiAl was studied using first-principles calculations. The calculation of formation energies of the NiAl alloys indicated the site preference of Re on the Ni sites. The valence band structures of the NiAl alloys were investigated by photoelectron spectroscopy. The valence band spectra of the NiAl with Re shifted away from the Fermi energy level so that the Ni d-band centroid moved to a higher energy by 0.25 eV as Re was added. Such a shift could be attributed to the Ni-Re interaction, which was supported by the photoelectron spectroscopy measurement.

Electronic and optical properties of vacancy-doped WS2 monolayers

Monolayers of tungsten disulfide doped with atomic vacancies have been investigated for the first time by density functional theory calculations. The results reveal that the atomic vacancy defects affect the electronic and optical properties of the tungsten disulfide monolayers. The strongly ionic character of the W-S bonds and the non-bonding electrons of the vacancy defects result in spin polarization near the defects. Moreover, the spin polarization of single W atomic vacancies has a larger range than for one or two S atomic vacancies. In particular, increased intensity of absorption and red shift of optical absorption are universally observed in the presence of these atomic defects, which are shown to be a fundamental factor in determining the spin transport and optical absorption of tungsten disulfide monolayers.

Near-infrared radiation absorption properties of covellite (CuS) using first-principles calculations

First-principles density functional theory was used to investigate the electronic structure, optical properties and the origin of the near-infrared (NIR) absorption of covellite (CuS). The calculated lattice constant and optical properties are found to be in reasonable agreement with experimental and theoretical findings. The electronic structure reveals that the valence and conduction bands of covellite are determined by the Cu 3d and S 3p states. By analyzing its optical properties, we can fully understand the potential of covellite (CuS) as a NIR absorbing material. Our results show that covellite (CuS) exhibits NIR absorption due to its metal-like plasma oscillation in the NIR range.

Solar radiation shielding material for windows TiN studied from first-principles theory

Using first-principles calculations in the framework of density functional theory, we studied the electronic structure and optical performance of TiN. It was found that the calculated structure parameter and optical performance are in better agreement with the latest relevant experimental data, and our theoretical studies showed that TiN is a perfect near infrared absorber with high visible light transmittance and could serve as references for future experimental study and its applications as solar radiation shielding material for windows.

Site preference of Ru in NiAl and valence band structure of NiAl containing Ru: First-principles study and photoelectron spectrum

The site preference of Ru in NiAl was studied using first-principles calculations. The calculation of formation energies indicated that the site preference of Ru was on the Ni sites. The valence band (VB) structures of the NiAl alloys were investigated by photoelectron spectroscopy. The VB spectra of the NiAl–Ru alloy was shifted away from the Fermi level so that the Ni d-band centroid moved to a higher energy by 7.77 eV as Ru was added. Such a shift revealed that the Ni–Ru interactions gave a significant contribution to the VB structure of the NiAl–Ru alloy.

First-principles prediction of solar radiation shielding performance for transparent windows of GdB6

The structural, electronic, magnetic, and optical properties of GdB6 are studied using the first-principles calculations. Calculated values for magnetic and optical properties and lattice constant are found to be consistent with previously reported experimental results. The calculated results show that GdB6 is a perfect near-infrared absorption/reflectance material that could serve as a solar radiation shielding material for windows with high visible light transmittance, similar to LaB6, which is assigned to its plasma oscillation and a collective oscillation (volume plasmon) of carrier electrons. It was found that the magnetic 4f electrons of Gd are not relevant to the important optical properties of GdB6. These theoretical studies serve as a reference for future studies.

THE EFFECTS OF CO-DOPING OF B AND N ON THE ELECTRONIC TRANSPORT OF SINGLE-WALLED CARBON NANOTUBES

Based on first-principle calculation, the geometry and electronic transport properties of the boron and nitrogen co-doping single-walled carbon nanotubes are investigated by using density functional theory combined with non-equilibrium Greens functions. The results show that the BN atoms energetically tend to form covalent bond of BN along axis in the nanotubes. In contrast to solely B or N doping, the co-doping do not generate accepter or donor subbands near the Fermi level. The co-doping give rise to the reduction of band gap in semiconducting (10, 0) tube and, furthermore, introduces the band gap to the metallic (5, 5) tube.