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Abstract:
CO adsorption on the polar ((1) over bar(1) over bar(1) over bar)
surface of the intermetaltic compound GaPd is examined within ab initio
methods using an all-electron full-potential electronic structure
approach. Comparison between the PW-LDA, GGA-PBE, GGA-RPBE, GGA-revPBE,
and hybrid HSE06 functionats is considered through bulk, clean surface
and CO adsorption calculations. The choice of the functional is found to
have a strong influence in the description of single CO adsorption on
the surface model proposed in literature. As expected from the so called
"CO adsorption puzzle", differences in the obtained results demonstrate
that classic LDA and PBE functionals can only partially describe the
complex CO adsorption bonding scenario on a surface containing
transition metal elements (in this case Pd atoms), where the energies of
the substrate-adsorbate electronic states are shifted, yielding
important differences in the absolute values of the adsorption energies,
vibrational frequencies and surface-adsorbate interaction. So far the
hybrid functional HSE06 correctly retrieves all the tendencies observed
experimentally as confirmed by comparing our first-principles results to
experimental findings.
