The gas phase structure and vibrational spectrum of tetrabromothiophene are calculated by ab initio methods. Unsealed DFT/B3LYP/TZVP frequencies fit conveniently well to the solid phase Raman spectrum and helped to establish the crystal space group. The unusual fit and the compounds' solidification into very small, irregularly arranged crystallites are correlated to the screening of the thiophene moiety by the bromine atoms.