where R hem/water the ITR of the hematite/water interface, R water is the thermal resistance of the water film and R water/P AO is the ITR of the water/PAO4 interface. The total ITR for the different FFs and water coverages is shown in Figure (a), and the contributions of each component are shown for each forcefield in Figure ). For the 0.5 and 1.0 ML films, the R water was assumed to be negligible as the films were ≤ 1 molecule thick. However, as the water coverage increases, this contribution becomes more significant. Even for the thickest water films, R water is much smaller than R water/P AO , which is due to the relatively high thermal conductivity of water compared to PAO. Hydroxylation affects the ITR differently depending on the strength of the hematite-PAO4 interactions. For weak (ClayFF ) and intermediate (INTERFACE-FF ) interactions, hydroxylation reduces the ITR compared to the anhydrous surface, as shown in Figure (a). This is surprising since hydroxylation reduces W sl , as shown in Figure . Our previous study showed larger ITR values for stronger W sl for the anhydrous surface. Instead, this reduction in ITR with hydroxylation could be due to the additional vibrational modes from the hydroxyls, which may lead to increased overlap in the vibrational density of states between the surface and the PAO4 molecules. Conversely, for the strong interactions (Savio et al. ), hydroxylation increases ITR by partially screening the hematite-PAO4 interactions.