= Statistical segment length
{title2=$b^2=\langle R^2\rangle/N$}
= Statistical step length
{synonym}
An effective step length describing a specified chain-count convention: an ideal <polymer> with $N$ counted units has mean-squared <end-to-end distance of a polymer chain> $\langle R^2\rangle=Nb^2$. If $N$ counts freely jointed coarse-grained units, $b$ is their <Kuhn length>. If $N$ counts chemical <repeat units>, the effective $b$ incorporates local conformational correlations and is not automatically a physical monomer diameter. A repeat-unit volume $v_0$ is independent information; setting $v_0\sim b^3$ is a scaling approximation.
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