“…Furthermore, the resulting low-temperature phase structures in CDW compounds like the quasi-one-dimensional K 0.3 MoO 3 [34,90,112,136], K 2 Pt(CN) 4 Br 0.3 •3.2 D 2 O (KCP) [34,108], NbSe 3 [34,137], ZrTe 3 [62,91], and (TaSe 4 ) 2 I [113], as well as the quasi-two-dimensional 2H-TaSe 2 [97] may be described as displacively modulated variants of a parent structure with incommensurate or commensurate q vector. Already above the actual transition temperature into the modulated phase all of the aforementioned materials show a regime of structural fluctuations that is characterized by the presence of distinct diffuse scattering and the critical growth of an elastic central peak in inelastic x-ray or neutron scattering spectra [34,62,90,91,97,108,112,113,136,137]. Yet, only K 0.3 MoO 3 [34,90,112] and ZrTe 3 [62,91] are affected by a simultaneous phonon softening of a non-zonecenter phonon mode close to zero energy in analogy to Sc 3 CoC 4 .…”