The ratio of the mean-square end-to-end distance,
, of a linear polymer
chain in a theta state to
is the number of rigid sections in the main chain, each of length
; if all of the rigid sections are not of equal length, the mean-square value of
is used, i.e.
In simple single-strand chains, the bonds are taken as the rigid sections. The recommended symbol is: (
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook