PCT curve prediction for Pd-alloyed hydrides. The excellent stability and reversible hydrogen absorption of Pd has led to its establishment as a benchmark material in the hydrogen storage community. The ability to model its thermodynamic equilibrium with hydrogen, i.e., the pressure-composition-temperature (PCT) curve, and a priori predict the affects of alloying are critical to both practically test any proposed thermodynamic modeling strategy and also inform rational tuning strategies for specific storage applications. 41,42 Now, Equation ( ) is modified to account for hydrogen atom occupation of the octahedral interstitial sites, and the idealized crystallographic input to the GNN is a concatenation of the alloyed FCC lattice and the interstitial lattice,