Energy level parameters for

Table VI. Estimated Values of Energy Level Parameters for Parametric Model, in cm-1.

Prediction of the energy level structure for Pu2+ (5f ) is of particular interest since no spectra for this valence state of Pu have been reported. On the basis of what is known of the spectra of Am2+ (26), Cf2" (27), and Es2+ (28), there appears to be evidence for a very small crystal-field splitting of the free-ion levels. Such evidence encourages use of a free-ion calculation in this particular case. The parameter values selected are indicated in Table V. Based on the systematics given by Brewer (19), the first f- d transition should occur near 11000 cm-, so the f- -f transitions at higher energies would be expected to be at least partially obscured. A... 

Table IV. Comparison of Energy Level Parameters Computed Using Hartree-Fock Methods and Those Evaluated from Fitting Experimental Data for An + (all in cm l).

Figure 8. Energy level diagram for exchange coupled Fe2+(SA = 2)-Fe3+(Ss = 5/2) dimer plotted versus the delocalization (double exchange) parameter B. The diagram is symmetric around B = 0.

The energy level diagram for Ti3+ in fig. 3.4 shows the manner by which the 2D spectroscopic term is resolved into two different levels, or crystal field states, when the cation is situated in an octahedral crystal field produced by surrounding ligands. In a similar manner the spectroscopic terms for each 3d" configuration become separated into one or more crystal field states when the transition metal ion is located in a coordination site in a crystal structure. The extent to which each spectroscopic term is split into crystal field states can be obtained by semi-empirical calculations based on the interelectronic repulsion Racah B and C parameters derived from atomic spectra (Lever, 1984, p. 126). 

Fig. 2. Energy level diagrams for HMO s. The data are qualitative and valid only for certain empirical parameters of the HMO method.

The +C(SH)3 cation and the radical dication derived from it have been the subject of high-level calculations. The ability of two adjacent suUur atoms to stabilize cations, anions, and radicals makes these species useful for relating bond-breaking and electron-transfer energies. Electrophilicity parameters for the dithiocarbenium ions (27) have been worked out, and the stabilities of the cations (28), (29) and (30) have been estimated using PM3 calculations. Cation (31) can be captured by solvent or azide ion, or it may ring close to (32), which subsequently alkylates another (31) cation as shown. 

Fig. 22 Energy level spectra for N = 0 through N = 3 states, starting with the seed state b, a Pd atom in a Cu surface site (N denotes the number of extra Cu atoms). Subsequent configurations result from the addition of Cu atoms in the overlayer. A (in eV/atom) indicates the difference in energy between any given configuration and the initial state in the chain (bA). The inset displays one of the configurations shown in the diagram, where a Pd atom is in a surface site and three Cu atoms occupy adjoining sites in the overlayer. In the Pd/Cu(110) case, a larger value of the ECT parameter X was used (A. = 10 A) in order to account for the asymmetry of the surface.

Typical energy-level schemes for dipolarly unstable systems with indications of the allowed rotational, tunneling, and tunneling-rotational transitions in two limit cases, when the rotational frequency is larger than the tunneling one and when the inverse inequality takes place, are presented in Figs. 1 and 2. The expected pure rotational spectra for three concrete sets of parameter values are shown in Figs. 3 to 5. If A = 0 (or... 

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