Additionally, lower-level methods have a reduced resolution in capturing subtle electronic interactions, effectively smoothing out near-degenerate energy levels that cause instability in more precise methods like PBE and TPSS. As a result, these methods are more robust and forgiving when dealing with systems like n-hexane, where symmetry and closely spaced orbitals create convergence challenges. A discussion on GitHub addresses convergence issues in time-dependent DFT calculations, particularly when dealing with near-degenerate states and the limitations of certain algorithms . To address the convergence issue, several strategies can be implemented such as adjusting SCF parameters (e.g., mixing, DIIS settings), using acceleration methods like MESA or ARH, and applying techniques like electron smearing or level shifting cautiously for stability, while monitoring their impact on results . Levi and his team worked on a direct optimization approach to DFT calculations, aiming to improve convergence in systems with unequally occupied degenerate orbitals . They established a robust direct optimization with a maximum overlap method, DO-MOM, for excited-state DFT calculations, overcoming challenges in saddle-point optimization using the limited-memory symmetric rank-one, L-SR1, Hessian update and avoiding variational collapse with MOM constraints, achieving improved convergence and robustness compared to SCF-MOM, particularly for charge-transfer and near-conical intersection states. • LSDA and dispersion-corrected DFT show lower deviations and better agreement with experimental results. • TPSSh shows the maximum deviations at n=10 (313.42 kcal/mol) when LSDA shows the minimum deviation of 30.67 kcal/mol for methane with split-valence basis set. • For cc-based basis set, TPSSh shows the maximum deviations at n=10 (265.96 kcal/mol) when LSDA shows the minimum deviation of 21.36 kcal/mol for n=1. 2. Percent Deviation: Deviation decreases with increasing the chain length.