ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
The contributions of the internal modes of urea molecules, CH4N2O, to the vibration tensors of their atoms are calculated at 0, 100 and 300 K. The calculations are based on IR and Raman date from the literature, and the force constants determined are of the Urey-Bradley type. The temperature dependence of the vibration tensors of the internal modes (diagonal components) is represented graphically in the 0-300 K region (interpolation over nine calculated points); in this region it is weak. Since, for urea, there are vibration tensors available which were determined by neutron diffraction, the contributions of the internal modes could be estimated. On average over the C, N, O atoms it is 1.8% at 300 K, 4.4% at 98 K and 5.8% at 60 K; on average over the H atoms it is 22.6% at 300 K, 39.9% at 98 K and 46.3% at 60 K.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0567739479001431
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