Many parameter errors are correlated in surface chemistry models. To investigate the e↵ect of accounting for the correlation between parameters, this study was conducted using both the uncorrelated 2 prior uncertainties and a prior covariance matrix. Since BEEF-vdW supplies an ensemble of 2000 values, an estimate of covariance can be obtained by performing the calculations referenced in Equations 4 through 7 on each of the energies obtained in the 2000 energy ensemble. This results in 2000 values of f H 0K,ads for each species. Equation 13 was used for each of the 169 pairs of species, resulting in a 13x13 grid of values.