We have investigated the evolution of the atomic and electronic structure of Sn deposited on the Ag(001) surface using low-energy electron diffraction (LEED), angle-resolved photoemission spectroscopy (ARPES), and density functional theory (DFT) calculations. We find that, for all Sn coverages $x$ up to 1 ML, the thermodynamically favoured configurations correspond to the formation of a bimetallic Sn-Ag substitutional surface alloy in the topmost layer. The LEED data reveal distinct superstructures for varying Sn coverages. We find that the effective sizes of Sn atoms on the Ag(001) surface are significantly larger than those of surface or bulk Ag atoms. As a result, the formation of the substitutional surface alloy relieves tensile stress at the surface. The theoretically computed “unfolded” band structure agrees excellently with ARPES data. Surprisingly, this is true even in cases where experiments and calculations suggest different atomic structures. Our findings suggest that the significant features in the band structure are predominantly influenced by the surface potential, which is less sensitive to the precise details of the atomic structure, but rather to the average surface composition.

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• Electronic structure
• Surface growth
• Angle-resolved photoemission spectroscopy
• Density functional theory
• Low-energy electron diffraction