Order parameter of aggregation and fluctuations

In order to distinguish between the fragmented and the aggregated regime, it is useful to introduce the order parameter [255] 

The summations are taken over the minimum distances dper = (c/per, rfper, dp ) of the respective centers of mass of the chains (or their periodic continuations). The center of mass of the /uth chain in a box with periodic boundary conditions is defined as fCOM,/ii = where ri is the coordinate vector of the first 

According to the Boltzmann distribution, we define canonical expectation values of any observable O by 

Formally, the integrations are performed over all possible conformations of the M chains. 

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