First-principles study of substrate-mediated interactions on a compressed Ag(111) surface

Scanning tunneling microscopy studies have revealed that monolayer-deep vacancy pits typically coarsen at 300 K via Smoluchowski ripening (SR) on Ag(111) surfaces and via Ostwald ripening (OR) on Ag(100) surfaces. We elucidate the underlying atomistic processes, the relevant energetics with some input from density functional theory analysis, and also the scaling of the ripening rate with mean pit size. Size scaling for SR reflects the size dependence of the pit diffusion coefficient, so we also discuss observed deviations from classical theories. SR dominates OR for pits on Ag(111) primarily due to its significantly lower effective energy barrier. However, the effective barrier for OR is not lower than that for SR for pits on Ag(100), and one must also account for the distinct size scaling of these pathways to explain the dominance of OR. We also briefly discuss the dependence on temperature of the dominant ripening pathway and the ripening behavior for adatom islands. Scanning tunneling microscopy studies have revealed that monolayer-deep vacancy pits typically coarsen at 300 K via Smoluchowski ripening ͑SR͒ on Ag͑111͒ surfaces and via Ostwald ripening ͑OR͒ on Ag͑100͒ surfaces. We elucidate the underlying atomistic processes, the relevant energetics with some input from density functional theory analysis, and also the scaling of the ripening rate with mean pit size. Size scaling for SR reflects the size dependence of the pit diffusion coefficient, so we also discuss observed deviations from classical theories. SR dominates OR for pits on Ag͑111͒ primarily due to its significantly lower effective energy barrier. However, the effective barrier for OR is not lower than that for SR for pits on Ag͑100͒, and one must also account for the distinct size scaling of these pathways to explain the dominance of OR. We also briefly discuss the dependence on temperature of the dominant ripening pathway and the ripening behavior for adatom islands.

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“…See Ref. 38 for similar observations on slow convergence for a strained-layer heteroepitaxial system.…”

Section: Appenidx B: Dft Analysis Of Energeticsmentioning

confidence: 64%

Ripening of monolayer vacancy pits on metal surfaces: Pathways, energetics, and size-scaling for Ag(111) versus Ag(100)

et al. 2007

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“…11,14,16 Theoretically, the lateral interactions can be directly derived from total energy ͑U͒ calculations of different coverages using density-functional theory ͑DFT͒. [17][18][19] The effect of entropy is included by performing kinetic Monte Carlo simulations using the obtained lateral interactions. 20 Recently, it was shown using STM that pairwise interactions are not always sufficient to describe the formed patterns 16,17 and many-body effects have to be taken into account.…”

Section: Introductionmentioning

confidence: 99%

Formation of ordered structures of NO on Rh(111)

2009

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In this work, several ͑unreported͒ structures of NO on Rh͑111͒ are presented for coverages ranging from 0-0.78 ML. The formation of these structures as evidenced experimentally by scanning tunneling microscopy ͑STM͒ images is explained using density-functional theory derived values for the lateral interactions and adsorption energies of NO on Rh͑111͒. Kinetic Monte Carlo simulations using the derived lateral interactions are performed to determine structures at finite temperatures. The resulting structures can be directly compared to the molecular arrangements observed in the STM experiment. The configuration of the first three structures that form for increasing coverage is the same both experimentally and theoretically. In all three structures, the molecules only occupy the fcc and hcp adsorption sites. Yet, at high coverage, at which the top adsorption sites become occupied, a discrepancy arises.

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“…10, the SS-mediated adatom interaction is calculated in the far-field regime for an Ag(111) surface using DFT. Our analysis agrees with their results, insofar as Eq.…”

Section: The Anisotropic Interaction On Ag(111)mentioning

confidence: 99%

“…Implicit differentiation of Eq. (2) with respect to k y , keeping k x fixed, gives V y (E, k x ); (10) where…”

mentioning

confidence: 99%

Anisotropic surface-state-mediated RKKY interaction between adatoms

Patrone

Einstein

2012

Phys. Rev. B

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Motivated by recent numerical studies of Ag on Pt(111), we derive an expression for the RKKY interaction mediated by surface states, considering the effect of anisotropy in the Fermi edge. Our analysis is based on a stationary phase approximation. The main contribution to the interaction comes from electrons whose Fermi velocity vF is parallel to the vector R connecting the interacting adatoms; we show that in general, the corresponding Fermi wave-vector kF is not parallel to R. The interaction is oscillatory; the amplitude and wavelength of oscillations have angular dependence arising from the anisotropy of the surface state band structure. The wavelength, in particular, is determined by the projection of this kF (corresponding to vF) onto the direction of R. Our analysis is easily generalized to other systems. For Ag on Pt(111), our results indicate that the RKKY interaction between pairs of adatoms should be nearly isotropic and so cannot account for the anisotropy found in the studies motivating our work. However, for metals with surface state dispersions similar to Be(1010), we show that the RKKY interaction should have considerable anisotropy.

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First-principles study of substrate-mediated interactions on a compressed Ag(111) surface

Cited by 24 publications

References 40 publications

Ripening of monolayer vacancy pits on metal surfaces: Pathways, energetics, and size-scaling for Ag(111) versus Ag(100)

Ripening of monolayer vacancy pits on metal surfaces: Pathways, energetics, and size-scaling for Ag(111) versus Ag(100)

Formation of ordered structures of NO on Rh(111)

Anisotropic surface-state-mediated RKKY interaction between adatoms

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