Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 40: Surface Dynamics

O 40.5: Vortrag

Dienstag, 18. März 2025, 15:00–15:15, H6

Out of the Crystalline Comfort Zone: Sampling the Initial Oxide Formation at Cu(111) — •Felix Riccius, Nicolas Bergmann, Hendrik H. Heenen, and Karsten Reuter — Fritz-Haber-Institut der MPG, Berlin, Germany

The oxidation of transition metal surfaces is widely recognized as a complex process that still bears many open questions, specifically at the microscopic level. Atomistic simulations could potentially uncover crucial insights, but state-of-the-art approaches are predominantly guided by human chemical intuition, leading to highly idealized surface representations. Here we demonstrate a systematic approach to model high-quality surface-phase diagrams, using the early oxidation of the Cu(111) surface as an example. To this end, we train a MACE machine learning interatomic potential (MLIP) to density functional theory calculations and combine its fast and accurate energetics with replica exchange molecular dynamics. We extensively explore the vast, thermodynamically relevant phase space and further develop surface phase diagrams based on increasingly involved theoretical frameworks. Our approach yields a comprehensive structural ensemble that predicts early Cu(111) oxidation to be characterized by O-Cu-O ring patterns, bearing significant disorder. Within the computed surface evolution, we recover trends in O-Cu-O ring distribution as a function of reaction conditions in line with scanning tunneling microscopy data. Our study illustrates how MLIPs and extensive sampling can be leveraged to rationalize metal surface oxidation fully in silico without the need to rely on experimental guidance.

Keywords: copper; oxidation; ab initio thermodynamics; surface modeling; statistical mechanics