Hydrides internuclear distance

The hydridic model is also naive, yet it provides a useful rationalization of internuclear distances in hydrides (as does the atomic model), and it permits estimation of their lattice energies. The latter is true only because the calculation of lattice energies by the method of Bom et al. (11) works reasonably well for solids which are not very ionic. 

When we plot the energy of the X state potential minimum relative to the energy of the ion pairs as a function of R the inverse of the internuclear distance at the minimum, we get a straight line correlation among the alkali hydrides (see Figure 1) ... 

Figure 4 shows the known RKR turning points for both the X and A states of the alkali hydrides. The internuclear distance is scaled by the equilibrium bond distance in the state. 

Figure 4. RKR turning points of the and states of the alkali hydrides plotted vs. the reduced internuclear distance R/Re. Key see Fig. 3.

The parameters A and p are determined by a nonlinear least square fit of equation (1) to the RKR inner turning points of each of the alkali hydrides. This fitting procedure is justified by the fact that the magnitude of the dipole moment functions of LiH (25, 26) and NaH (33) at these internuclear distances are very close to those of opposite point charges a distance R apart. 

New spectroscopic measurements of the alkali hydrides have provided information related to the dynamical charge transfer process for these systems. We have examined the RKR potentials derived from these spectra. Several striking regularities for the X l potentials are presented along with an interpretation based on a simple model of ionic potentials for internuclear distances shorter than the crossing distance R. . 

Figure 1.2 shows kR plotted against the Pauling electronegativity, for all the diatomic hydrides where the data is available. The quantity kR, where k is the force constant and Rq the internuclear distance, is simply the force that the atom X exerts on the H atom. This force is a good measure of what the bond energy would be without the interference of promotion energies. 

Fluorine hydride (FH). The FH ground state (J S+) PEC calculations have been performed in the range of the internuclear distances Re [0.64, 4.0] A. The correlation-consistent aug-cc-pVTZ basis set [65, 66] has been used in the calculations. 

The silver hydride diatomic molecule, Ag H, has an internuclear bond distance of 1.617 A. Predict the energies, in joules, of its first four rotational levels. (Use / = ixi. )... 

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