Response functions for noninteracting chains

We first define the response functions for a noninteracting stem of chains (which would fill the lattice at random, each site then being allowed to carry more than one monomer). Later we introduce the interactions. Consider one ideal chain, and ask for the conelation 

At this point we may note the relationship with the E)ebye scattering function goiq) introduced in Chapter I. This function arises when we superpose equal scattering amplitudes on all monomers. With the normalization of Chapter I, it is 

We also find it useful to consider sums of the responses Stun over one index, defining 

Physically 5 describes the response of the nth monomer to perturbations which act equally on all monomers in an ideal chain. 

Now we have listed all our tools. The next problem is to proceed from ideal chains to strongly interacting chains. 

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