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Abstract:
The energetics of an Au adatom and AuN clusters (N = 2–6) supported on pristine and reduced
MgO(100) surfaces is analyzed using an all-electron full-potential density functional theory approach. A
hierarchy of exchange-correlation functional approximations is employed, ranging from the generalized
gradient approximation [Perdew-Burke-Ernzerhof (PBE), revised PBE (RPBE)] to hybrid functionals [PBE0,
Heyd-Scuseria-Ernzerhof (HSE06)] to exact exchange plus correlation in the random phase approximation
(EX-cRPA/cRPA+). The analysis of different terms in the electronic Hamiltonian, contributing to calculated
adhesion energies (Eadh) for the Au adatom, shows that reducing the self-interaction error leads to smaller
Eadh values. On the contrary, the energy barriers for diffusion of an Au adatom at the pristine surface
significantly increase. For AuN clusters (N >1), dispersion effects, not accounted for by the generalized gradient
approximation or hybrid functionals, start to make an increasingly important contribution to the adhesion energy.
