Landau–Peierls instability

Landau–Peierls instability refers to the phenomenon in which the mean square displacements due to thermal fluctuations diverge in the thermodynamic limit and is named after Lev Landau (1937) and Rudolf Peierls (1934). This instability prevails in one-dimensional ordering of atoms/molecules in 3D space such as 1D crystals and smectics and also in two-dimensional ordering in 2D space such as a monomolecular adsorbed films at the interface between two isotrophic phases.

Source: Wikipedia — Landau–Peierls instability (CC BY-SA 4.0)