Understanding surface–adsorbate bonding in chemically intuitive terms remains a central challenge in computational surface science. In this talk, I will present a molecular-orbital-based analysis of H₂ adsorption and dissociation on Cu(111) and the Pd/Cu(111) single-atom alloy using density functional theory in combination with LOBSTER-based bonding tools. Projected densities of states, crystal orbital Hamilton populations, crystal orbital bond indexes, and Löwdin population analyses are used to connect familiar molecular concepts—forward donation, back-donation, and bond order—to periodic metal surfaces. Application of these tools shows how adsorption progressively weakens the H–H bond while strengthening H₂–surface interactions along the dissociation pathway. Compared with Cu(111), Pd/Cu(111) lowers the calculated H₂ dissociation barrier by stabilizing the transition state through localized charge redistribution at the Pd site and stronger H₂–metal bonding interactions. This work demonstrates how modern orbital-projection methods can translate plane-wave DFT results into bonding descriptions that are accessible to molecular chemists and useful for interpreting reactivity at catalytic surfaces.
