Figure 5: Four different example distortions in crystals and their distortion symmetry groups.

Each panel depicts the superimposed structures through a distortion from λ=−1 to λ=+1 so that the movement of the atoms appears in the form of a blur. (a) A distortion pathway between two domain variants of a right-handed alpha quartz, passing through beta quartz at λ=0, with a distortion group of P6₄22. (b) A distortion of ferroelectric PbTiO₃ created by a linear interpolation between opposite (180°) polarization states; the pathway has a symmetry of P4/mmm. (c) A distortion of YMnO₃ between opposite ferroelectric domain variants with a distortion symmetry of P6₃/mcm. (d) A B_1u normal mode of YBa₂Cu₃O_6.5 with a distortion symmetry of Pmmm.