Density Functional Theory (DFT) calculations for this study were performed using Gaussian 16 software to compute the enthalpy and Gibbs free energy of combustion reactions for alkanes . Total 10 alkane molecules, from methane (C1) to decane (C10), were considered. Initial molecular geometries of the alkanes, oxygen, carbon dioxide, and water were downloaded in SDF format from PubChem . The geometries were verified through visual inspection and optimized with UFF force field and Steepest Descent algorithm using Avogadro software . The energetically stable molecules were then converted to Gaussian input files (.com) with associated checkpoint files (.chk) using the Extensions of Avogadro software. This ensured accurate and consistent input structures for computational analysis in Gaussian software. All calculations utilized various DFT functionals with the 6-31G(d) and cc-pVDZ basis sets .