Figure presents a detailed comparison of the infrared (IR) spectra obtained using both Density Functional Theory (DFT) and Hartree-Fock (HF) methods for isomers a, b, and c, as derived from the data in Table of the study by Gurka and Titus. Upon close examination, a significant difference in the effectiveness of these two computational approaches becomes apparent. The IR spectra generated by the DFT method show a higher number of distinct peaks, corresponding to various functional groups within the TCBD molecule, in stark contrast to the relatively sparse peaks in the HF-derived spectra. This difference is particularly notable because the HF method is expected to produce reliable spectra for small molecules, yet the similar shapes of the DFT spectra indicate its superior performance. In contrast, the HF spectra, despite the structural similarities of the isomers, show more variation, a surprising result that underscores the limitations of the HF method. Notably, only isomer c could be accurately characterized using HF, except for the C-H stretch, which should exhibit a medium-intensity peak around 3100-3000 cm⁻¹. This observation further emphasizes that DFT outperforms HF in its ability to provide a detailed and accurate depiction of molecular structures, particularly when identifying the functional groups within complex molecules like TCBD.