Vibrational Potential Energy Distributions and Coriolis Coefficients for Extremal Force Constants in Bent XY2, Pyramidal XY3, and Tetrahedral XY4 Molecules

1970 ◽  
Vol 25 (2) ◽  
pp. 217-221 ◽  
Author(s):  
D.E. Freeman

Abstract For 27 molecules with approximately extremal force fields, an empirical distinction between hydrides and non-hydrides is linked, via the comparison of calculated and observed Coriolis coefficients, to a difference, based ultimately on the relative lightness of the hydrogen atom, in the potential energy distributions of hydrides and non-hydrides. The potential energy criteria of Becher and Ballein are compared to those corresponding to extremal diagonal force constants. Coriolis coefficients for the model of progressive rigidity are mostly in rough agreement with those observed.

1983 ◽  
Vol 61 (2) ◽  
pp. 263-266 ◽  
Author(s):  
A. Annamalai ◽  
Surjit Singh

The redundancy-free internal valence force field of monomeric acetic acid is evaluated using CNDO/force calculations and least-squares refinement. The initial force field is set up by taking the interaction and bending force constants from CNDO force field and transferring the stretching force constants from the force fields of chemically related molecules. Vibrational frequencies of monomeric CH3COOH, CH3COOD, CD3COOH, and CD3COOD are used to refine the force constants. The experimental force field thus obtained is found to be reasonable when compared to the force fields of related molecules as well as on the basis of the frequency fits and potential energy distributions.


1970 ◽  
Vol 25 (4) ◽  
pp. 566-569
Author(s):  
M. N. Avasthi ◽  
M. L. Mehta

Abstract Wilson's GF matrix method has been used to evaluate all the seven independent force constants of some XY6 type ions using Müller's mathematical constraint. Mean amplitudes of vibration and Bastiansen-Morino shrinkages have also been calculated for these ions.


1973 ◽  
Vol 27 (3) ◽  
pp. 209-213 ◽  
Author(s):  
John F. Jackovitz ◽  
Charles E. Falletta ◽  
James C. Carter

Infrared and Raman spectra for (K+) (CF3BF3−) have been obtained from 4000 to 50 cm−1. Spectral assignments were made on the basis of C3v symmetry using both 10B and 11B compounds. In addition, a normal coordinate analysis was performed to obtain the potential energy distribution of the normal modes. A Urey-Bradley type force field was used, and force constants obtained for the CF3 and BF3 groupings were compared to those in C2F6 and BF4−.


1979 ◽  
Vol 34 (3) ◽  
pp. 362-368 ◽  
Author(s):  
A. F. Demiray ◽  
W. Brockner ◽  
B. N. Cyvin ◽  
S. J. Cyvin

AbstractNormal coordinate analyses of the chlorotitanate ions Ti2Cl102−Ti2Cl9− - and TiCl5− have been carried out following Wilson's FG matrix method. The final force constants are given in terms of symmetry coordinates, which are thoroughly specified for a Ti2Cl9− molecular model. Assignments of the vibrational frequencies of the title compounds are proposed, and the corresponding potential energy distributions are given. The final force fields were used to calculate the mean amplitudes of vibration, of which those of TiCl5− and selected values of Ti2Cl102− andTi2Cl9− are reported.


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