The root mean square errors (RMSE) referenced to DFT values were used as the metric to evaluate the accuracy of the DP; these are shown as parity plots in Figure . The RMSE in predicted energies are 1.1 × 10 -3 eV/atom and 1.4 × 10 -3 eV/atom for the uncharged and charged sets, respectively. This is within so-called "chemical accuracy" of 0.04 eV. The corresponding RMSE in predicted forces are 0.074 eV/ Å and 0.088 eV/ Å, respectively.