| Summary: | We unravel the origin of the recently observed striking enantioselectivity of the PdGa(l1l) surface with respect to the adsorption of a small organic molecule, 9- ethynylphenanthrene, using first-principles calculations. It turns out that the key ingredient to understand the experimental evidence is the appropriate description of van der Waals interactions beyond the widely employed atomic pairwise approximation. A recently developed van der Waals-inclusive density functional method, which encompasses dielectric screening effects, reveals the origin of the experimentally observed enantioselectivity and provides conclusive evidence of chiral recognition on a bimetallic surface driven by dispersion interactions. The incorporation of dielectric screening leads to a renormalization of the dispersion interaction range, allowing for the appropriate weighting of the molecule -- substrate interactions at intermediate distances between 2.5 and 5 Á Our findings have implications for the structure and stability of complex organic/inorganic systems where dielectric screening effects are expected to be of general importance.
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