In terms of the scaling relationships, Figure shows that all four energy components (electrostatic, polarization, van der Waals, and charge transfer) for CH x (x = 1, 2, 3) adsorption exhibit remarkable linear correlations with the corresponding values for the adsorbed carbon atom. The R 2 values are all above 0.80, which are comparable to the R 2 values for the total adsorption energies in Figure . Among all energy components, the linear scaling relations in Figure ) for the charge transfer energies are especially robust, with R 2 reaching 0.93-0.99.