Further, we investigated whether fitting the U parameter to calculations performed on isolated SBUs at the CCSD(T) level of theory, considered the gold standard, could help in predicting the experimental heat of adsorption. The calibrated parameter, termed U CCSD(T) , showed varying degrees of success. For N2 adsorption, the PBE+U CCSD(T) calculations exhibited improved accuracy over the standard PBE calculations in cases where PBE was prone to overbinding. However, the impact of U CCSD(T) was minimal for CO2 adsorption, which is primarily driven by physisorption. O2 adsorption presented additional challenges, particularly due to uncertainties in spin states upon adsorption. The U CCSD(T) parameter, while correcting the overbinding in PBE calculations for O2, leads to overcorrections in certain systems, highlighting the need to consider the full spin configuration.