Vibrational spectral analysis, computation of thermodynamic functions for various temperatures and NBO analysis of 2,3,4,5-tetrachlorophenol using ab initio HF and DFT calculations

► 2,3,4,5-Tetrachlorophenol are studied by HF and B3LYP and B3PW91 for C1 and C2 conformers. ► Total energy calculations of 2,3,4,5-tetrachlorophenol are tried for the possible conformers. ► All results are compared with experimental FT-IR and FT-Raman spectra. ► The thermodynamic parameters were obtained for the range of temperature 100-1000 K. ► The chemical parameters were calculated from the HOMO and LUMO values.