Understanding global infrared opacity and hot bands of greenhouse molecules with low vibrational modes from first-principles calculations: the case of CF4

2018 ◽  
Vol 20 (32) ◽  
pp. 21008-21033 ◽  
Author(s):  
Michaël Rey ◽  
Iana S. Chizhmakova ◽  
Andrei V. Nikitin ◽  
Vladimir G. Tyuterev
Keyword(s):  
Global Warming ◽  
First Principles ◽  
Vibrational Modes ◽  
First Principles Calculations ◽  
Atmospheric Lifetime ◽  
The Future ◽  
Global Warming Potentials

Fluorine containing molecules have a particularly long atmospheric lifetime and their very big estimated global warming potentials are expected to rapidly increase in the future.

scholarly journals First-Principles Study on the Stabilities, Electronic and Optical Properties of GexSn1-xSe Alloys

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 876 ◽  
Author(s):  
Qi Qian ◽  
Lei Peng ◽  
Yu Cui ◽  
Liping Sun ◽  
Jinyan Du ◽  
...  
Keyword(s):  
Optical Properties ◽  
Solar Cells ◽  
Band Gap ◽  
Electronic Properties ◽  
First Principles ◽  
Future Application ◽  
First Principles Calculations ◽  
Electronic And Optical Properties ◽  
Direct Bandgap ◽  
The Future

We systematically study, by using first-principles calculations, stabilities, electronic properties, and optical properties of GexSn1-xSe alloy made of SnSe and GeSe monolayers with different Ge concentrations x = 0.0, 0.25, 0.5, 0.75, and 1.0. Our results show that the critical solubility temperature of the alloy is around 580 K. With the increase of Ge concentration, band gap of the alloy increases nonlinearly and ranges from 0.92 to 1.13 eV at the PBE level and 1.39 to 1.59 eV at the HSE06 level. When the Ge concentration x is more than 0.5, the alloy changes into a direct bandgap semiconductor; the band gap ranges from 1.06 to 1.13 eV at the PBE level and 1.50 to 1.59 eV at the HSE06 level, which falls within the range of the optimum band gap for solar cells. Further optical calculations verify that, through alloying, the optical properties can be improved by subtle controlling the compositions. Since GexSn1-xSe alloys with different compositions have been successfully fabricated in experiments, we hope these insights will contribute to the future application in optoelectronics.

Energy distributions of neutrons scattered from solid C60 by the beryllium detector method

1995 ◽  
Vol 73 (11-12) ◽  
pp. 763-771 ◽  
Author(s):  
J.R. D. Copley ◽  
D. A. Neumann ◽  
W. A. Kamitakahara
Keyword(s):  
Energy Range ◽  
First Principles ◽  
Spectroscopic Data ◽  
Vibrational Modes ◽  
First Principles Calculations ◽  
Energy Distributions ◽  
Gaussian Functions ◽  
Detector Method ◽  
Normal Vibrational Modes ◽  
Rich Spectrum

We measured the energy distribution of neutrons scattered from polycrystalline C60, using a high-resolution filter-analyzer spectrometer. In the energy range 30–90 meV (242–726 cm−1) we observed a rich spectrum that we fitted to a sum of 15 Gaussian functions, each of which is assigned to one or a set of several degenerate normal vibrational modes of the C60 molecule. We also observed two broad features in the energy range from 90–130 meV (726–1049 cm−1). Our results are generally in excellent agreement with published spectroscopic data. Detailed comparisons with the results of several first-principles calculations suggest that present-day theories can predict the internal vibrational frequencies of C60 rather well, at least in the 30–90 meV range of energies.

scholarly journals Stability, diffusion, and complex formation of beryllium in wurtzite GaN

2000 ◽  
Vol 639 ◽  
Author(s):  
Sukit Limpijumnong ◽  
Chris G. Van de Walle ◽  
Jörg Neugebauer
Keyword(s):  
Complex Formation ◽  
First Principles ◽  
Formation Energy ◽  
Potential Problem ◽  
Vibrational Modes ◽  
First Principles Calculations ◽  
Experimental Identification ◽  
Donor Character ◽  
Formation Of Complexes

ABSTRACTWe have studied the properties of Be dopants in GaN using first principles calculations. Substitutional Be on a Ga site acts as an acceptor, but interstitial Be poses a potential problem because of its low formation energy and donor character. We study the diffusion of interstitial Be and find it to be highly anisotropic. We also study the formation of complexes between substitutional and interstitial Be, and between substitutional Be and hydrogen. We have calculated the Be-H vibrational modes to aid in experimental identification of such complexes.

scholarly journals Anomalous vibrational modes in few layer WTe 2 revealed by polarized Raman scattering and first-principles calculations

2D Materials ◽  
2017 ◽  
Vol 4 (3) ◽  
pp. 035024 ◽  
Author(s):  
Yan Cao ◽  
Natalya Sheremetyeva ◽  
Liangbo Liang ◽  
Hui Yuan ◽  
Tingting Zhong ◽  
...  
Keyword(s):  
Raman Scattering ◽  
First Principles ◽  
Vibrational Modes ◽  
First Principles Calculations ◽  
Polarized Raman

Anharmonicity in the Vibrational Modes Associated with H-H, N-H, O-H, and C-H bonds

2004 ◽  
Vol 813 ◽  
Author(s):  
Sukit Limpijumnong
Keyword(s):  
First Principles ◽  
Vibrational Frequency ◽  
Vibrational Mode ◽  
Harmonic Approximation ◽  
Vibrational Modes ◽  
First Principles Calculations ◽  
Local Vibrational Mode ◽  
Free Molecules

ABSTRACTThe anharmonic contributions to the vibrational frequency of various H-H, N-H, O-H, and C-H bond configurations are investigated using first principles calculations. While harmonic approximation can be accurately used to calculate the local vibrational mode of most microscopic configurations, the configurations involving strong X-H bond are exceptions because of the exceptionally light mass of the H atom. We will explicitly present the magnitude of the anharmonic contributions to the total frequencies associated with X-H bonds in free molecules as well as in semiconductors defects.

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