Density functional theory (DFT) has become a powerful tool for predicting NMR chemical shifts, enabling the study of complex molecular systems . Information in Table suggests that the B3PW91 functional is able to produce more accurate δC, which agrees well with Wang et al , whereas the B3LYP functional produces better δH, which agrees with what Stoychev et al and de Oliveira et al discovered. In this section, we compare the relative performance of B3LYP and B3PW91 on the accuracy of NMR predictions. By validating our theoretical methods with experimental data, we aim to promote the broader use of the combined DFT-NMR approach in future studies of fuel isomerism and related systems. For proton δH chemical shifts, the B3LYP functional slightly outperforms B3PW91 (Figure (b)).