Chapter 5. Vibrational problem in symmetry coordinates

1973 ◽  
Vol 28 (11) ◽  
pp. 1787-1793 ◽  
Author(s):  
S. J. Cyvin ◽  
V. Devarajan ◽  
J. Brunvoll ◽  
Ø . Ra

The molecular vibrations of cyclic (HF)6 are studied. The consequences of complex characters for irreducible representations of the appropriate point group (C6h) are elucidated. The secular equation of the vibrational problem is solved in terms of real coordinates. Those of the degenerate species were obtained by a transformation of the complex symmetry coordinates. The force constants were taken from solid HF data. Mean amplitudes of vibration were calculated and compared with electron diffraction results.


1971 ◽  
Vol 54 (4) ◽  
pp. 1517-1522 ◽  
Author(s):  
S. J. Cyvin ◽  
J. Brunvoll ◽  
Lothar Schäfer

1964 ◽  
Vol 40 (3) ◽  
pp. 743-753 ◽  
Author(s):  
J. Murphy ◽  
H. H. Caspers ◽  
R. A. Buchanan

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.


1976 ◽  
Vol 31 (12) ◽  
pp. 1589-1600 ◽  
Author(s):  
Lennart Lyhamn ◽  
S. J. Cyvin ◽  
B. N. Cyvin ◽  
J. Brunvoll

Abstract A complete vibrational analysis is performed for the 53 atomic PMo12O40 model of Td symmetry. The symmetry coordinates are classified into those of (a) ligand vibrations, (b) framework-ligand couplings, (c) framework vibrations, and (d) interligand vibrations. Simple valence force fields are estimated, and the influence of inclusion of redundancies on the calculated frequencies and symmetry force constants is investigated. Comments are made on calculated symmetry force constant values up to 345 mdyne/Å. Vibrational frequencies are calculated for the Mo3O7 and Mo3O13 units and for the PMo12O403- complex ion. For the latter compound the calculated values are compared with experimental data from infrared and Raman spectra.


1990 ◽  
Vol 45 (5) ◽  
pp. 641-646 ◽  
Author(s):  
J. Thesing ◽  
W. Preetz

Normal coordinate analyses for the ten isotopomers Cs211Bn10B6-nH6, n = 0 — 6, including the pairs of geometric isomers for n = 2, 3, 4 have been performed, based on a general valence force field. The shift of the bands as well as the splitting of degenerate modes by lowered symmetry due to exchange of 10B by 11B or H by D is exactly calculated by a set of six force constants. The characteristic band patterns observed in the IR and Raman spectra of Cs2B6H6 with natural abundance of B isotopes (80.22% 11B, 19.78% 10B) measured at 10 K are explained by the superposition of the calculated spectra of the different isotopomers present, according to their statistical frequency distribution. The calculated atomic displacements and the potential energy distribution on the symmetry coordinates reveal only a small coupling (PED < 10%) between the cage (in-phase displacements of H and B) and substituent vibrations (anti-phase motions of B and H). Based on the normal coordinate analyses previously obtained assignments for several bands are revised.


1964 ◽  
Vol 20 (6) ◽  
pp. 1065-1070 ◽  
Author(s):  
William H. Fletcher ◽  
Charles S. Shoup ◽  
William T. Thompson

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