Mean amplitudes of vibration

Venkateswavlu, K., and V. Malathy Devi Mean Amplitudes of Vibration XY3Z Type of Silicon Compounds. Current Sci. [Bangalore] 1965, 373-374. 

Mean Amplitudes of Vibration Molecules of the XY2Z2 Type. 

Table 6 Mean Amplitudes of Vibration (A) for Thia- and Selena-diazoles (3), (4) and (6)...

The saturated vapour pressure of HF has been redetermined for the temperature range 273—303 K 167 this leads to a calculated boiling point of 292.90 K, at which temperature the association factor is estimated to be 3.75. Raman scattering by monomeric HF in the gaseous state and at low concentration in liquid SF6 has been studied by Le Duff and Holzer 168a Birnbaum has confirmed that rotational fine structure is evident in the far-i.r. spectrum in solution in SF6.1681 The Raman work also yielded some results on the HF polymer bands at 2900—3800 cm 1 these were said to be consistent with the presence of hexameric and tetrameric species.1680 The mean amplitudes of vibration of the cyclic hexamer (HF)6 have been calculated169 and the results compared with those from electron diffraction. 

There have been a large number of determinations of molecular force constants, mean amplitudes of vibration, bond asymmetry parameters, Coriolis coupling constants (and inertia defects) and centrifugal distortion constants [146,152,259,271,304,581,840,1221,1222,1278,1312, 1416,1448,1449,1549,1550,1575-1578,1587,1618,1671,1682,1806,1807,1858,1931,1961,1984,2021,2045, 2108,2109-2111,2167a], as well as a determination of the atomic potential energy distribution... 

NAG2] Nagarajan, G., Mean amplitudes of vibration and thermodynamic... 

Estimations of the mean amplitudes of vibration for metal—oxygen bonds in MO (M = Mo or W) have been reported together with a force constant of 3.7 mdyne forWO . Raman andi.r. vibrational data for Mo 0 "and Mo 04 ... 

In a discussion of mean amplitudes of vibration, hedberg questioned their sensitivity to the specific force field, mills felt they were not very sensitive, although he had not made many calculations, crawford concurred that, although the normal coordinates themselves are uncertain, the mean square amplitudes (which involve summation) are not sensitive to the particular force field, lord pointed out that an exception occurs for molecules having highly anharmonic, large... 

In addition to isotope frequency shifts, mean amplitudes of vibration, Coriolis coupling constants, centrifugal distortion constants, and so forth may be used to refine the force constants of small molecules (see Ref 81). 

Force constants and mean amplitudes of vibration were evaluated. The Tc=0 bond proved to be by far the strongest, exhibiting force constants of more than 8 mdyne/A [92]. 

The 21 fundamental vibrations of thiophene are composed of eight vibrations of A, symmetry, seven of B, symmetry, and three each of A2 and B2. The assignments of all 21 vibrations have been documented by Rico et al. as early as 1965 <65SA689> and are listed in Table 8. Based on these frequencies, harmonic force constants, and mean amplitudes of vibration have been developed... 

The character of a chemical bond is associated to its vibrational frequency. Bonds with low force constants possess high vibrational frequencies and small amplitudes of vibration and are rigid, while those with large mean amplitudes are the most reactive. Ionic and polar bonds fall into this latter category. The fundamental frequencies of a molecule can be obtained from vibrational spectra. From this, it is possible to calculate the force field which in turn, is used to obtain the mean amplitudes of vibration for the individual bonds in a molecule. This process has been studied in the Group 16 five-membered heterocycles <85MI 209-03). 

The symmetric and asymmetric C—stretching frequency decreases as one goes down the column from oxygen to tellurium while the interatomic distances increase. This implies a decrease in the force constants and a corresponding increase of the mean amplitudes of vibration. The C—O bond is thus more rigid than the C—Te bond. The force constants for the C=C is found to increase in... 

Force constants, Coriolis coupling constants, and mean amplitudes of vibration of InCl have also been calculated from previously reported vibrational data. The stretching force constants of the isoelectronic sequence are in the following order InCl < SnClg" < SbCl. ... 

VIBRATIONAL SPECTRA, POTENTIAL ENERGY CONSTANTS, MEAN AMPLITUDES OF VIBRATIONS AND CALCULATED THERMODYNAMIC PROPERTIES OF ACETAMIDE. 

The mean amplitudes of vibration of the interesting IF - anion (D4d-sym-metry), containing iodine (VII), were calculated from known spectroscopic and structural data in the temperature range between 0 and lOOOK The results are discussed in comparison with those of related species. 

Mean amplitudes of vibration are very useful and valuable parameters for the analysis of molecular structures and their vibrational behavior. In a similar way to vibrational frequencies and force constants, they can be very characteristic values for both bonded and nonbonded atoms [1,2]. 

During years we have calculated mean amplitudes of vibration for a large series of molecules and ions containing halogen-halogen or halogen-oxygen bonds... 

The mean amplitudes of vibration were calculated with the method of the characteristic vibrations of Muller et al. [8] (cf. also [2,9]). The necessary vibrational-spectroscopic data were taken from the recent paper of Dixon et al. [4] and the geometrical parameters from the paper of Mahjoub and Seppelt [5]. 

Table 1. Mean amplitudes of vibration (in A) for the IF - anion in the temperature range between 0 and 1000 K.

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