Static dielectric permeability

Critical distances [32] of ion stabilization in organic solids for the rectangular, Rrcr, and the Coulomb, Rccr, forms of the barrier for electron tunneling, and critical coefficients, -D, of ion diffusion as functions of the ionization energy, 7d, of the donor, and the static dielectric permeability of a solid,... 

The frequency dependence explains why the dielectric permeability of water measured in a static electric field is 81, but at optic frequencies is only 1.77 in the first case all polarization mechanisms are participating in the polarization but in the latter case only electron polarization takes place. 

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