Force constant calculations for

The spectra of S12 and Si2-CS2 clearly reflect the differing site symmetries of the S12 molecule The two Eg vibrations at 188 and 245 cm degenerate in Si2 CS2, split into their components in pure S12 with its non-degenerate site symmetry of C2h- The valence force constants calculated for S12 reproduce the observed wavenumbers within 14 cm [79]. The two most interesting constants are/r = 2.41 and/ r = 0.60 N cm ... 

Kofraneck and coworkers24 have used the geometries and harmonic force constants calculated for tram- and gauche-butadiene and for traws-hexatriene, using the ACPF (Average Coupled Pair Functional) method to include electron correlation, to compute scaled force fields and vibrational frequencies for trans-polyenes up to 18 carbon atoms and for the infinite chain. 

Force constant calculations for the in-plane vibrations of PtyX /t-X) - show that the terminal stretching force constants are larger than the bridging stretching force constants but that the difference diminishes for the heavier halides.1920... 

Zerbi G (1977) Limitations of Force Constant Calculations for Large Molecules, chapt 17. In Bames AJ, Orville-Thomas WJ (eds) Vibrational Spectroscopy - Modem Trends. Elsevier, Amsterdam, p 261... 

Comparison of aeometries and force constants calculated for H 0 with... 

Some attention has been given to the calculation of force constants for the system cis-M(CO)3X2Y. Dobson et al. found that the ratio ki (XX) ki (XY) has a critical value, below which real roots are obtained for the secular equations (172, 173). It was concluded that as the force constants k and ky, when real, are relatively insensitive to changes in the ratio ki (X.X) ki (XY), values for the force constants calculated for the critical value can be assumed to be reasonable. Stone et al., however, suggested that force constant data corresponding to the maximum value of the interaction constant k (XY) and thus to the maximum coupling between the two a modes are most reliable this postulate was justified by calculations using a band attributed to the CO-substituted derivatives (118). 

Force constant and inertia defect calculations have been performed for COCIF [604,1312,1531,1549,1550,1575-1578]. CNDO calculations have been used to calculate (> C=0) for COCIF [1680], and the fundamental frequencies for COCIF have been calculated from the force constants calculated for COXj (X = F, Cl or Br) [1578]. 

Group V Donors. The i.r. and Raman spectra of mixed metal complexes of the type [(NH3)5RuN20s(NH3)5]Br4 have been recorded. Approximate force constants calculated for [Os(NH3)5N2]Br2 and related complexes were calculated and the M—Nj—M vibrations in the dinuclear complexes analysed. 

Force constant calculations for Ni(PF3)4 (190, 326) indicate that K(P-F) is similar to that in free trifluorophosphine and the metal-phosphorus force constant (about 2.4 mdyne/A), is only in the range expected for a single bond. Very recently, structural data for Ni(PF3)4 have become available from electron diffraction studies (la, 279a) (Section IX,C) and the phosphorus-fluorine bond length (1.561 ... 

Most of the force constants calculated for TC2O7 turn out to be smaller than the corresponding force constants calculated for Rc207. Smaller bond-stretching force constants were also found for [TcCl6p and [TcBrgj- than for the analogous complexes of rhenium [52]. 

Mills, I. M. (1963). Force constant calculations for small molecules. In Infra-red Spectroscopy and Molecular Structure (ed. M. Davies), pp. 166-98. Amsterdam Elsevier Pub. Co. [14]... 

TABLE 9.8. Unsealed and Scaled MNDO Force Constants Calculated for the Soliton and... 

The i.r. and Raman intensities of the stretching vibrations of MegHg and MeHgX compounds in solution and a review of force constant calculations for MeHgX have been published. ... 

IR and Raman assignments were given for SSbX, where X = Cl or Br, on the basis of Cs symmetry. The first force constants calculated for these species were reported." The Raman spectrum of (CuI)2Cu3SbS3 contains bands due to SbS3 - at 362,338cm-. ... 

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