Ab Initio Optoelectronic Properties of Silicon Nanoparticles: Excitation Energies, Sum Rules, and Tamm–Dancoff Approximation

2014 ◽  
Vol 10 (8) ◽  
pp. 3290-3298 ◽  
Author(s):  
Dario Rocca ◽  
Márton Vörös ◽  
Adam Gali ◽  
Giulia Galli
Keyword(s):  
Ab Initio ◽  
Silicon Nanoparticles ◽  
Sum Rules ◽  
Optoelectronic Properties ◽  
Excitation Energies

Sum rules and mean excitation energies for longitudinal isoscalar electroexcitation of nuclei

1977 ◽  
Vol 16 (2) ◽  
pp. 812-815 ◽  
Author(s):  
E. Lipparini ◽  
G. Orlandini ◽  
R. Leonardi
Keyword(s):  
Sum Rules ◽  
Excitation Energies

Experimental and ab-initio investigation of the microstructure and optoelectronic properties of FCM–CVD-prepared Al-doped ZnO thin films

2019 ◽  
Vol 125 (9) ◽  
Author(s):  
Ilyass Jellal ◽  
Hassan Ahmoum ◽  
Yassine Khaaissa ◽  
Khalid Nouneh ◽  
Mourad Boughrara ◽  
...  
Keyword(s):  
Thin Films ◽  
Ab Initio ◽  
Optoelectronic Properties ◽  
Zno Thin Films ◽  
Doped Zno

scholarly journals Molecular Data for Stellar Opacities

1995 ◽  
Vol 10 ◽  
pp. 576-578
Author(s):  
Uffe Gråe Jørgensen
Keyword(s):  
Ab Initio ◽  
Energy Levels ◽  
Laboratory Data ◽  
Molecular Data ◽  
Molecular Ions ◽  
Molecular Constants ◽  
Excitation Energies ◽  
Line Intensities ◽  
Lower Accuracy ◽  
Ab Initio Computations

In total, 40 neutral diatomic molecules, 2 molecular ions, and 7 polyatomic molecules are known from observed photospheric stellar spectra. Line data for opacity computations (i.e., lists of line frequencies, intensities, and excitation energies) exist for 17 of these molecules, although the data are complete only for a handful of them. A detailed description of stellar photospheric molecules can be found in Tsuji (1986), and the existing opacity data have been reviewed by Jorgensen (1995).Listed line frequencies in the data bases are either the measured values, or based on computed molecular constants obtained from fits to measured values. Attempts to compute ab initio line frequencies have so far resulted in lower accuracy than what is obtained by use of molecular constants. Published line strengths include measured values as well as ab initio values. For strong bands the ab initio intensities are as accurate as the laboratory values, whereas measured values for weak bands are generally more accurate than the ab initio values. The primary advantage of ab initio computations is therefore that the complete set of all transitions can be obtained. Exploratory studies have shown that completeness of the line data is crucial for the obtained stellar photospheric structure.As an alternative to the ab initio computations of the line intensities, fits to experimental data have been attempted. The most promising method seems to be to fit the dipole function by use of a Padé approximant. Combined with a potential fitted to experimental energy levels, such a dipole function can in principle be used to predict the complete list of band intensities and line intensities for all bands with energies up to the molecular dissociation energy. The part of the dipole function which corresponds to the largest stretching (or bending) of the molecule is the most uncertain in such fits as well as in ab initio computations. This part is responsible for most of the many weak transitions, and large uncertainties are therefore to be excepted in the computed intensities of the weak spectral bands. As these are of major importance for the stellar photospheric structure (due to their huge number and their pseudo continuous appearance in the spectrum), a particularly large effort is desirable in comparing computed intensities with laboratory data for a representative sample of weak bands. Unfortunately, only few measurements of weak bands exist.

scholarly journals New van der Waals Heterostructures Based on Borophene and Rhenium Sulfide/Selenide for Photovoltaics: An Ab Initio Study

2021 ◽  
Vol 11 (24) ◽  
pp. 11636
Author(s):  
Michael M. Slepchenkov ◽  
Dmitry A. Kolosov ◽  
Olga E. Glukhova
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Materials Science ◽  
Van Der Waals ◽  
Optoelectronic Properties ◽  
Visible Range ◽  
Van Der Waals Heterostructures ◽  
Uv Detectors ◽  
High Absorption Coefficient ◽  
Rhenium Sulfide

One of the urgent tasks of modern materials science is the search for new materials with improved optoelectronic properties for various applications of optoelectronics and photovoltaics. In this paper, using ab initio methods, we investigate the possibility of forming new types of van der Waals heterostructures based on monolayers of triangulated borophene, and monolayers of rhenium sulfide (ReS), and rhenium selenide (ReSe2), and predict their optoelectronic properties. Energy stable atomic configurations of borophene/ReS2 and borophene/ReSe2 van der Waals heterostructures were obtained using density functional theory (DFT) calculations in the Siesta software package. The results of calculating the density of electronic states of the obtained supercells showed that the proposed types of heterostructures are characterized by a metallic type of conductivity. Based on the calculated optical absorption and photocurrent spectra in the wavelength range of 200 to 2000 nm, it is found that borophene/ReS2 and borophene/ReSe2 heterostructures demonstrate a high absorption coefficient in the near- and far-UV(ultraviolet) ranges, as well as the presence of high-intensity photocurrent peaks in the visible range of electromagnetic radiation. Based on the obtained data of ab initio calculations, it is predicted that the proposed borophene/ReS2 and borophene/ReSe2 heterostructures can be promising materials for UV detectors and photosensitive materials for generating charge carriers upon absorption of light.

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