Figure 1:
The chiral tetragonal phase of elemental tellurium as a result of multiple charge order. (a) The distortion pattern of a one-dimensional chain with a two-third filled band, described by the displacements u=cos(qx), with q=2π/3a. (b) The same one-dimensional pattern repeated throughout a three-dimensional simple cubic lattice. The displacements are given by u=cos(Q⋅r)x̂, with Q=(q,q,q) and x̂=(1,0,0). (c) The chiral combination of three differently polarized one-dimensional patterns with a relative phase difference of ϕ=2π/3. The distortion pattern u=(cos(Q⋅r),cos(Q⋅r+ϕ),cos(Q⋅r+2ϕ)) coincides with the tetragonal lattice structure of Te. The chirality of the pattern is indicated by the corkscrewlike arrow following the double bonds in the final structure.