Editing Rotamer (section)

===Factors contributing to the free energy of conformers===
The effects of [[electrostatics|electrostatic]] and [[steric effects|steric]] interactions of the substituents as well as orbital interactions such as [[hyperconjugation]] are responsible for the relative stability of conformers and their transition states. The contributions of these factors vary depending on the nature of the substituents and may either contribute positively or negatively to the energy barrier. Computational studies of small molecules such as ethane suggest that electrostatic effects make the greatest contribution to the energy barrier; however, the barrier is traditionally attributed primarily to steric interactions.<ref>{{cite journal|last=Liu|first=Shubin|title=Origin and Nature of Bond Rotation Barriers: A Unified View|journal=The Journal of Physical Chemistry A|date=7 February 2013|volume=117|issue=5|pages=962–965|doi=10.1021/jp312521z|pmid=23327680|bibcode=2013JPCA..117..962L}}</ref><ref>{{cite book|last=Carey|first=Francis A.|title=Organic chemistry|url=https://archive.org/details/organicchemistry00care_486|url-access=limited|year=2011|publisher=McGraw-Hill|location=New York|isbn=978-0-07-340261-1|page=[https://archive.org/details/organicchemistry00care_486/page/n139 105]|edition=8th}}</ref>
[[File:Contributions to Rotational Energy Barrier.png|center|thumb|450px|Contributions to rotational energy barrier]]
In the case of cyclic systems, the steric effect and contribution to the free energy can be approximated by [[A value]]s, which measure the energy difference when a substituent on cyclohexane in the axial as compared to the equatorial position. In large (>14 atom) rings, there are many accessible low-energy conformations which correspond to the strain-free diamond lattice.<ref>{{cite journal |doi=10.1007/s40828-015-0014-0 |url=https://link.springer.com/content/pdf/10.1007/s40828-015-0014-0.pdf |title=Conformational analysis of cycloalkanes |year=2015 |last1=Dragojlovic |first1=Veljko |journal=Chemtexts |volume=1 |issue=3 |page=14 |bibcode=2015ChTxt...1...14D |s2cid=94348487 }}</ref>