This susceptibility type is derived from the KKR susceptibility type which is described above. The only difference is that after the computation of the real part (via the Kramers-Kronig transformation) the value of the real part for zero frequency is subtracted in the whole spectral range. This drags down the real part to zero for low wavenumbers.

Note that this behaviour of a susceptibility is quite unphysical. Usually any polarizability mechanism with some dynamics can instantly follow the slowly varying electric fields for low wavenumbers which is described by a positive real static dielectric constant. For high wavenumbers with time scales far below the response times of the mechanism no polarization is excited and the susceptibility should approach zero. In KKR susceptibility II objects the situation is - due to the subtraction of the static real part - reverse and  hence not very recommendable from a physical point of view. However, there might be situations where the introduction of this susceptibility type could be useful.

Susceptibilities of this type must be combined with other contributions that add to the real part of the dielectric functions. Good choices are the types 'Constant' and 'Constant refractive index'.