Centrosymmetric-noncentrosymmetric structural phase transition in the quasi-one-dimensional compound (TaSe4)3I

${({\text{TaSe}}₄)}₃\text{I}$, a compound belonging to the family of quasi-one-dimensional transition metal tetrachalcogenides, has drawn significant attention due to a recent report on the possible coexistence of two antagonistic phenomena, superconductivity and magnetism below 2.5 K (Bera et al., arXiv:2111.14525). Here, we report a structural phase transition of the trimerized phase at temperature $T\phantom{\rule{0.16em}{0ex}}\ensuremath{\simeq}145$ K using Raman scattering, specific heat, and electrical transport measurements. The temperature-dependent single-crystal x-ray diffraction experiments establish the phase transition from a high-temperature centrosymmetric to a low-temperature noncentrosymmetric structure, belonging to the same tetragonal crystal family. The first-principles calculations find the aforementioned inversion symmetry-breaking structural transition to be driven by the hybridization energy gain due to the off-centric movement of the Ta atoms, which wins over the elastic energy loss.