Editing Liquid crystal (section)

===Elastic continuum theory===
{{See also|Distortion free energy density}}
In this formalism, a liquid crystal material is treated as a continuum; molecular details are entirely ignored. Rather, this theory considers perturbations to a presumed oriented sample. The distortions of the liquid crystal are commonly described by the [[Frank free energy density]]. One can identify three types of distortions that could occur in an oriented sample: (1) twists of the material, where neighboring molecules are forced to be angled with respect to one another, rather than aligned; (2) splay of the material, where bending occurs perpendicular to the director; and (3) bend of the material, where the distortion is parallel to the director and molecular axis. All three of these types of distortions incur an energy penalty. They are distortions that are induced by the boundary conditions at domain walls or the enclosing container. The response of the material can then be decomposed into terms based on the elastic constants corresponding to the three types of distortions. Elastic continuum theory is an effective tool for modeling liquid crystal devices and lipid bilayers.<ref>{{cite journal|title = Continuum theory for nematic liquid crystals| journal=Continuum Mechanics and Thermodynamics|volume = 4|date= 1992| issue =3| page = 167| doi =10.1007/BF01130288|bibcode = 1992CMT.....4..167L| vauthors = Leslie FM | s2cid=120908851}}</ref><ref>{{cite journal | vauthors = Watson MC, Brandt EG, Welch PM, Brown FL | title = Determining biomembrane bending rigidities from simulations of modest size | journal = Physical Review Letters | volume = 109 | issue = 2 | pages = 028102 | date = July 2012 | pmid = 23030207 | doi = 10.1103/PhysRevLett.109.028102 | bibcode = 2012PhRvL.109b8102W | doi-access = free }}</ref>