Moire Patterns\nin Pt Overlayers on Gold: A\nGraph Neural Network Interatomic Potential Study

Overlayer structures in bimetallic catalysts are relevant\nto a\nvariety of catalytic reactions, particularly in electrocatalysis for\nfuel cell applications. Previous computational studies largely consider\nthese overlayer structures to be those of a pseudomorphic overlayer,\nwhere there is a 1:1 atomic ratio between the overlayer and the support\nmetal. Our previous work based on density functional theory (DFT)\nhas shown that there exist nonstoichiometric overlayer structures\nthat are more stable than the stoichiometric ones. In this work, we\ndeveloped a graph neural network interatomic potential (GNN-IP) to\nanalyze structures formed in Pt overlayers on Au(111). The GNN-IP\nwas used to explore properties of nonstoichiometric overlayers at\nlength scales that are prohibitively expensive to pursue with planewave\nDFT calculations. In particular, we examined large Pt islands on top\nof a 48 × 48 Au(111) unit cell to explore the influence of the\nrotational angle (α) between the Pt overlayer and support Au(111)\non both the stability of and the preferred atomic density in the overlayer.\nIsland structures with smaller rotational angles between the Pt overlayer\nand Au(111) tend to be more stable. Further, smaller rotational angles\ntend to result in lower atomic density in the Pt overlayer.