Surface model and exchange-correlation functional effects on the description of Pd/α-Al2O3(0001)

Abstract

The interaction of Pd with the Al-terminated ␣-Al 2 O 3 (0001) surface has been investigated using an embedded cluster model and periodic-supercell approaches. Furthermore, several treatments of electronic exchange and correlation within density functional ͑DF͒ theory have been employed including generalized gradient approximation ͑GGA͒ and hybrid exchange functionals. In the periodic calculations the influence of pseudopotentials and basis sets have also been investigated by comparing GGA results obtained using all electron basis set and pseudopotential plane-wave approaches. For a given choice of the exchange-correlation functional and for a fixed substrate, the cluster and slab models predict nearly the same structural parameters and adsorption energies. All structural models reproduce the general trend for the interaction of Pd with the ␣-Al 2 O 3 (0001) surface, which is that there is a slight preference for adsorption above surface sites sitting directly above oxygen atoms either from the second or fifth layer. However, significantly larger differences exist when comparing different DF methods within a given surface model. The cluster and periodic slab models predict a large adsorbate-induced relaxation with a similar description of the metal-oxide interface provided a minimum number of surface layers is included in the optimization procedure.

Adhesion trends and growth mode of ultra-thin copper films on MgO

“…This package uses the localized, LCGTF basis set where each crystalline wavefunction is constructed as a linear combination (LC) of atom-centred Gaussian-type functions (GTFs). In the present study, we use the non-local generalized gradient approximation (GGA) for both exchange and correlation functionals, which have shown earlier very reasonable results in CRYSTAL-DFT calculations on the metal adhesion on the metal oxide interfaces [14]. The most appropriate description of the regular Cu/MgO(001) interface is achieved using Becke's non-local, hybrid (DFT-HF), three-parameter exchange-correlation functional B3LYP [15].…”

Controlling the spin of metal atoms adsorbed on oxide surfaces: Ni on regular and defective sites of the MgO(001) surface

“…15,38 -40 On the other hand, the combined use of cluster and periodic models gives us a complete picture for low and high coverage properties. 18 For the planar surface, an embedded stoichiometric cluster model containing 13 O and 13 Mg atoms has been used; the central O atom has been removed when representing a vacancy. In both cases the cluster is surrounded by total ion potentials ͑TIPS͒, that represent Mg cations in direct contact to the O atoms in the edges of the cluster and by an appropriate array of point charges ͑PC͒ with formal absolute values of 2.…”

Accounting for van der Waals interactions between adsorbates and surfaces in density functional theory based calculations: selected examples

“…For instance, clusters embedded in large arrays of point charges and effective core potentials (ECP) were proven to be quite useful to study metal oxide surfaces such as those of MgO 58,59 or a-Al 2 O 3 . [60][61][62] An example of an embedded cluster model with three different regions that was used to model the MgO(100) surface is shown in Fig. 1.…”