Electronic energy gap correlation function and spectral density of anharmonic molecules at low temperatures. II: Spectroscopy

2015 ◽  
Vol 629 ◽  
pp. 18-22 ◽  
Author(s):  
Mohamad Toutounji
2017 ◽  
Vol 63 (No. 8) ◽  
pp. 363-369
Author(s):  
Mikleš Milan ◽  
Helexa Milan ◽  
Mikleš Juraj

The issue of terrain conditions is very complex and its description is approached from different perspectives and with different objectives. Because it consists of the gathering of basic information for a mobile object, a wheeled forestry tractor, the terrain-vehicle approach was taken as the basis. Ground conditions are part of the operating conditions of wheeled forestry tractors. Uneven ground can be regarded as a source of vibration in the vehicle – towing truck. In this respect, given the random shape of the surface roughness, the solution to vibrations leads to a terrain correlation analysis in order to obtain a correlation function and power spectral density of the ground surface. Scanning of the ground micro-profile was performed using a device for quick terrain scanning, which from the mechanical aspect consists of a towing vehicle and a measuring carriage. Correlation function and power spectral density are the evaluation based on ground micro-profile measurements and the results of calculations. Measurements of forest terrain (road) micro-profile were done in the area of Little Fatra and Little Carpathians in Slovakia. In geological terms, the measurements were done in an area with the occurrence of gneiss, granite, limestone and flysch. No measurements were performed in a sandy area.


2021 ◽  
Author(s):  
Vera Meerson ◽  
O. Khorolsky

The article discusses the application of some of the most important time windows for spectral density estimation determined by the correlogram method (from correlation function) and the periodogram method (from direct fourier transform).


2013 ◽  
Vol 78 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Mihajlo Etinski

The intersystem crossing rates of uracil and thymine molecules in interaction with the heat bath were studied by means of the ab initio methods. The rates were calculated employing the time-dependent approach based on the correlation function. The normal modes of the singlet and triplet electronic states were related by the Duschinsky transformation. The correlation function was calculated using the Condon approximation for the spin-orbit matrix element and harmonic approximation for the nuclear motion. The excess vibrational energy in the initial singlet excited electronic state decreases the rate of the triplet formation in uracil and thymine. This decrease is more pronounced for uracil. Also, it was found that the change of the adiabatic energy gap can significantly modify the rate of the triplet formation.


1987 ◽  
Vol 42 (10) ◽  
pp. 1273-1281 ◽  
Author(s):  
Walter Abriel ◽  
Ernst-Jürgen Zehnder

AbstractFrom theoretical considerations a dynamically distorted octahedron as a result of vibronic coupling between the ground state and the first excited state should exist for 14 electron AX6E systems like TeX62- . A high symmetry crystal field yielding at least a center of symmetry for the Te position stabilizes this fluctuating structure, otherwise statical distortion will be observed. From X-ray diffraction experiments on antifluorite type compounds A2TeX6 (A = Rb. Cs: X = Cl, Br) the averaged structure (m3̅m symmetry) of the anions was found even at very low temperatures. The thermal parameters are not significantly different from those of similar SnX62 compounds. Distortions therefore are very small and are evident from FTIR spectroscopic meas­urements only. Here very broad T1u-deformation vibration bands are observed down to tempera­tures <10 K without splitting: Astatically distorted species could not be frozen out. In contrast to XeF6 for TeX62- the energy gap between the threefold, fourfold or sixfold minima of the potential surface (according to the symmetry of one component of the T1u-vibration) is very small and shifted to temperatures lower than reached with the devices used for these experiments.


1998 ◽  
Vol 51 (1) ◽  
pp. 131
Author(s):  
Jie Jiang

We study the magnetic transition and spin correlation in Mn oxides at low temperatures. The results indicate that there are antiferromagnetic (AF), spiral (SP), ferromagnetic (FM) and canted (CN) states when T → 0. With temperature increasing, a paramagnetic (PM) state appears. The spin–spin correlation function is also obtained.


2020 ◽  
Vol 102 (19) ◽  
Author(s):  
Vitaly Gorelov ◽  
David M. Ceperley ◽  
Markus Holzmann ◽  
Carlo Pierleoni

1999 ◽  
Vol 259-261 (1-2) ◽  
pp. 345-346 ◽  
Author(s):  
S Gabáni
Keyword(s):  

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