Average Debye screening constant

Figure 32 The PB (solid lines) and DH (dashed lines) potential and field profiles as a function of the distance from the center of a charged capillary of radius 20 A with surface charge density = —0.01 sq/A in the absence of added salt (only counterions are present) according to Eqs. [286], [288], and [291] the effect of using an average Debye screening constant in the DH expressions is shown by dotted lines.

Here fl,- is the force constant for atom i and is the thermally averaged mean-square displacement for atom i in the protein the latter quantity is proportional to the crystallographically determined Debye-Waller factor if static disorder is neglected (see Chapt. VI). To simplify the treatment, average mean-square displacements can be used to represent the different types of atoms. The factor 5(r,) is an empirical scaling function that accounts for the interatomic screening of particles which are away from the RZ-RR boundary, 108 it varies from 0.5 at the reaction zone boundary to zero at the reaction region (see Fig. 8). 

A key quantity in the Debye-Huckel theory, leading to the values of the constants A and B, is the screening length, k, the average reciprocal of the radius of the ionic atmosphere surrounding an ion in the solution, made up essentially by ions of the opposite charge. The square of this quantity is proportional to the ionic strength of the solution and also to the reciprocal of the product w T ... 

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