At low temperatures, linear alkanes C_nH_(2n+2) of moderate length are known to prefer a fully extended (all-trans) conformation, in analogy to the simplest case of butane. Owing to weak dispersion interactions between chain segments, this cannot hold up to n→∞. Only a finite, quite moderate amount of energy is required to bend an extended chain into a hairpin structure by four trans-gauche isomerizations. With increasing n, the self-solvation between the two aligned chain segments grows and will win over the deformation energy at some point. The theoretical minimum structure predicted for a given n will depend sensitively on the details of the alkane model.
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