In this study, we selected the B3LYP/cc-pVTZ model for calculations. While B3PW91 offers better accuracy for certain junction carbons in C-NMR predictions, B3LYP provides a more balanced performance across both C-NMR and H-NMR chemical shifts, especially for the hydrogens of interest. Since we aim to reveal the properties of the exo-TCD chair and boat isomers in isolation, without solvent interactions, the gas-phase calculations using B3LYP are appropriate. Furthermore, the slightly lower RMSD in H-NMR predictions with B3LYP suggests that this functional is better suited for capturing the subtle interactions in the chair and boat isomers of exo-TCD. The balance between accuracy and computational efficiency makes B3LYP/cc-pVTZ a reliable choice for the detailed structural and spectroscopic analysis of JP-10 isomers.