Vibrational spectroscopy and DFT calculations of 1,​3-​dibromo-​2,​4,​6-​trimethylbenzene: Anharmonicity, coupling and methyl group tunneling

International audienceThe Raman, IR and INS spectra of 1,3-dibromo-2,4,6-trimethylbenzene (DBMH) were recorded in the 80-3200 cm-1 range. The molecular conformation and vibrational spectra of DBMH were computed at the MPW1PW91/LANL2DZ level. Except for the methyl 2 environment, the agreement between the DFT calculations and the neutron diffraction structure is almost perfect (deviations < 0.01 Å for bond lengths, < 0.2° for angles). The frequencies of the internal modes of vibration were calculated with the harmonic and anharmonic approximations; the later method yields results that are in remarkable agreement with the spectroscopic data, resulting in a confident assignment of the vibrational bands. Thus, no scaling is necessary. The coupling, in phase or anti-phase, of the motions of symmetrical C-Br and C-Me bonds is highlighted. Our DFT calculations suggest that the torsion of methyl groups 4 and 6 is hindered in deep wells, whereas methyl group 2 is a quasi-free rotor. The failure of the calculations to determine the frequencies of the methyl torsional modes is explained as follows: DFT does not consider the methyl spins and assumes localization of the protons, whereas the methyl groups must be treated as quantum rotors

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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Calibration and validation of a switched linear macroscopic traffic model

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Molecular evidence of Rickettsia slovaca in spleen of wild boars in northeastern Algeria

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Probabilistic analysis of slope stability towards the slip by the kinematic method

AbstractThe analysis of slope stability or a slope is a complex problem that requires careful reflection and common sense. In effect because of the diversity of sites and especially their heterogeneity, each case is unique, the stability check is done by studying the general failure along the slip surface that is superficial, shallow, deep or very deep by conventional methods found in the literature such as the Bishop method, Jumbu, Fellenius etc. ... based on the determination of global minimum factor of safety.In this paper, we propose a mechanical model for calculating the failure along the sliding surface based on the kinematic method of rigid solids (Limit analysis).The statistical-probabilistic concept of safety is a very useful tool for comparison because it reflects the dispersion of random parameters (geometry, intrinsic characteristics of the soil load, etc. ...) will be applied to this model, the reliability of the system will expressed using the reliability index.The introduction of the concept of reliability index Geotechnical is a valuable tool capable of giving the engineer a greater objectivity in the design of slopes.We determine the critical slopes and the corresponding costs from the state equation R-S=0 limit of the present mechanism. Finally recommendations will be given for modeling the failure along the sliding surface [10]