The errors and costs of the lowest cost ARGP models that give errors below 2 and 1 kJ mol -1 are listed for all three molecules in Table , along with the most expensive 70%/70% models. For oxalic acid, the 40%/10% model yields errors below 1 kJ mol -1 with a cost corresponding to only 4.2% of the cost of PBE0 calculations on all crystal structures. Similar savings are possible for maleic hydrazide and urazole, yielding errors below 1 kJ mol ), calculated on 2.0 GHz Intel Skylake processors.