Kondo parameter

In Fig. 4 we show results for a spin-boson system at low temperature and large Kondo parameter where the linearization approximation is expected to do most poorly. Indeed, in this situation we see a significant discrepancy between the results of our linearized calculations and exact values. The linearized path integral approximation overemphasizes the effect of the friction, and underestimates the importance of the coherent dynamics. Thus the exact result oscillates around zero while the linearized approximate result is overdamped and shows slow incoherent decay. 

This spectral density has a characteristic low-frequency behavior J((o) — rjo), where rj is the usual ohmic viscosity. The system-bath coupling strength can then be measured in terms of the dimensionless Kondo parameter K, and time scale of bath motions is described by a cutoff frequency (o. For many problems in low-temperature physics, this cutoff frequency is taken to be the largest frequency scale in the problem. In the case of electron transfer, the same spectral density with some intermediate value for is most appropriate for a realistic description of... 

Figure 1. Potential profile ij/(x) across the cell wall (x < 0) according to the simplified expression (6) from the Ohshima and Kondo model [15]. The profile within the solution (x > 0) is assumed to follow the usual GC decay expression ij/ = ij/Dm exp ( — kx) (equation (2)). Parameters T — 298 K, z—+1, = 78.5, thickness of the Donnan layer = 10 nm, p — 1447Cdm Curves correspond with c — 0.2, 0.1, 0.05, 0.02 and...

Our Kondo temperature is set by parameters of the small dot. For small (large) dot of diameter 100mn(2pm) in a GaAs/AlGaAs heterostructure, it is possible to achieve um 3K > Tk IK Am 50mA. ... 

Nakajima T, Kondo Y. Well-differentiated cholangiocarcinoma diagnostic significance of morphologic and immrmohistochemi-cal parameters. Am J Surg Pathol. 1989 13 569-573. 

Because the rate of the reaction wiU be proportional to the concentration of the transition state, which is in turn related to K, we woidd expect that a plot of In k versus solubihty parameter would be Hnear. We are assuming in this case that the decrease in the free energy of activation is directly proportional to the ability of the solvent to force the formation of the transition state. Figure 5.6 shows a test of this relationship using the data given by Kondo, et al. (1972) for the reaction of benzylbromide with pyridine, which is the represented by Eq. (5.126). It can be seen that for most of the solvents the relationship is approximately correct. 

FIGURE 5.6 Relationship between the rate constants for the reaction shown in Eq. (5.126) and the solubility parameter of the solvent. (Constructed using the data of Kondo, et al. (1972).)... 

The theory of intermediate valence (IV) forms the starting point for the treatment of HF materials. IV represents the limiting situation of a very strong coupling parameter g in strongly correlated electron materials, as can be seen from fig. 105. Kondo insulators in particular possess IV behavior at high temperatures as an essential ingredient. They form a borderline case. We have discussed them earlier as a separate class of materials. 

The groimd-state properties of Kondo-lattice systems, for example, are expected to be very sensitive to external pressure. The latter may modify the strength of the exchange interaction J between the localized 4f and the conduction electrons and thereby the competition between the intersite (RKKY) and intrasite (Kondo) interactions. The balance between these effects has been theoretically described by Doniach (1977) for a magnetic phase diagram depending on the exchange parameter J. 

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