Radial force constant tables

Chadi and Martin (1976) used essentially the same LCAO parameters that are given in the Solid State Table to obtain the energies at the two special points in the Brillouin Zone. They then redetermined the wave numbers of the special points for the distorted crystal and recalculated the energy. The clastic distortion which they used is a shear strain, in which there is no change in bond length to first order in the strain thus the radial force constant ofEq. (8-1) docs not enter the calculation. That strain can be written as... 

For characterizing a dipolar molecule in its electronic ground state, few methods are more instructive than pulsed-nozzle Fourier-trans-form microwave spectroscopy (32). As illustrated schematically in Fig. 5, a short pulse of microwave radiation directed at the gas pulse excites a rotational transition in the species of interest subsequently the rotationally excited molecules reemit radiation, which is detected. This technique provides a remarkably sensitive probe for transients, the properties of which can be specified with all the precision and detail peculiar to rotational spectroscopy only microseconds after their production. In relation to a weakly bound adduct A --B formed by two molecular reagents A and B, for example, we may draw on the rotational spectrum to determine such salient molecular properties as symmetry, radial and angular geometry, the intermolecular stretching force constant and internal dynamics, the electric charge distribution, and the electric dipole and quadrupole moments of A -B (see Table I). 

In this case, analytic formulas can also be obtained for the second derivatives that govern the harmonic vibrations [10]. Table 2 lists the vibrational force constants and normal mode frequencies determined [10, 12] using Wilson s FG matrix treatment, the procedure standard for molecular vibrations [14]. The radial displacements from the minimum are combined in the usual way to form symmetry coordinates,... 

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