Diffusion of small Cu islands on the Ni(111) surface: A self-learning kinetic Monte Carlo study

Acharya, Shree Ram; Shah, Syed Islamuddin; Rahman, Talat S.

doi:10.1016/j.susc.2017.03.012

Cited by 14 publications

(10 citation statements)

References 59 publications

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“…Here, an island is considered as a structure where each atom is connected with at least one nearest neighbour. Based on an extensive study of post-adsorption diffusion kinetics of small islands of Cu/Ni(111) and Ni/Cu(111) as a function of the island size [28,39], it is concluded that, in addition to single-atom diffusion, the most executed diffusive events correspond to concerted diffusion of complete islands with size up to eight atoms and concerted two-atom diffusion along the step-edge of compact islands. Thus, the current study focuses on including these particular diffusion events.…”

Section: Identification Of Diffusion Eventsmentioning

confidence: 99%

“…For each identified diffusion event, the activation energy barrier (E k α ) is calculated by using the drag method while describing the interaction between the atoms with a many-body semi-empirical embedded atom model (EAM) [37]. The EAM + drag combination produces qualitative and semi-quantitative results with minor errors for metallic systems when compared with ab initio energetics, including island diffusion barriers on fcc(111) [28,38]. For this study, the substrate consists on five fcc(111) layers with 16 × 16 = 256 atoms per layer, where the two bottom layers are kept frozen (to mimic the bulk) while the three top layers are allowed to relax.…”

Section: Calculation Of Energy Barriers and Ratesmentioning

confidence: 99%

“…For the actual simulations, we use the standard, rejectionfree, time-dependent implementation of the kinetic Monte Carlo (KMC) method with periodic boundary conditions [27,35,38,28,43]. A flowchart of the KMC procedure is presented in figure 4.…”

Section: Kinetic Monte Carlomentioning

confidence: 99%

“…the diffusion of more than one adatom at once. Although there are theoretical studies on (i) the diffusivity of a single monomer of Cu (Ni) on Ni (Cu) [28,29] and (ii) a more complete growth picture of Cu/Ni(111) [30,31] and Ni/Cu(111) [32,33,34], in this study we consider a large variety of single-atom, multi-atom and complete-island diffusion events, with the aim of obtaining a general picture on the relative importance of concerted diffusion in twodimensional material growth, applied to metals.…”

Section: Introductionmentioning

confidence: 99%

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On the validity of the Arrhenius picture in two-dimensional submonolayer growth

Alberdi-Rodriguez,

Acharya,

Rahman

et al. 2019

Preprint

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For surface-mediated processes, such as on-surface synthesis, epitaxial growth and heterogeneous catalysis, a constant slope in the Arrhenius diagram of the corresponding rate of interest against inverse temperature, log R vs 1/k B T , is traditionally interpreted as the existence of a bottleneck elementary reaction (or rate-determining step), whereby the constant slope (or apparent activation energy, E R app ) reflects the value of the energy barrier for that reaction. Here, we show that a constant value of E R app can be obtained even if control shifts from one elementary reaction to another. In fact, we show that E R app is a weighted average and the leading elementary reaction will change with temperature while the actual energy contribution for every elementary reaction will contain, in addition to the traditional energy barrier, a configurational term directly related to the number of local configurations where that reaction can be performed. For this purpose, we consider kinetic Monte Carlo simulations of two-dimensional submonolayer growth at constant deposition flux, where the rate of interest is the tracer diffusivity. In particular, we focus on the study of the morphology, island density and diffusivity by including a large variety of single-atom, multi-atom and complete-island diffusion events for two specific metallic heteroepitaxial systems, namely, Cu on Ni(111) and Ni on Cu(111), as a function of coverage and temperature.

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Section: Identification Of Diffusion Eventsmentioning

confidence: 99%

Section: Calculation Of Energy Barriers and Ratesmentioning

confidence: 99%

Section: Kinetic Monte Carlomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the validity of the Arrhenius picture in two-dimensional submonolayer growth

Alberdi-Rodriguez,

Acharya,

Rahman

et al. 2019

Preprint

Self Cite

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show abstract

“…the abundance of that event type in the given surface configuration. Compared to previous approaches focussed on monitoring the execution of all event types [38], the use of the multiplicities offers an alternative route for the determination of the actual numbers of executed events. Most importantly, we show that an examination of the temperature dependence of the multiplicities enables resolving unambiguously the dominant contributions to the apparent activation energy of the diffusivity.…”

Section: Introductionmentioning

confidence: 99%

Dominant contributions to the apparent activation energy in two-dimensional submonolayer growth: comparison between Cu/Ni(111) and Ni/Cu(111)

Alberdi-Rodríguez

Acharya²,

Rahman³

et al. 2020

J. Phys.: Condens. Matter

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For surface-mediated processes in general, such as epitaxial growth and heterogeneous catalysis, a constant slope in the Arrhenius diagram of the rate of interest, R, against inverse temperature, log R vs 1/T, is traditionally interpreted as the existence of a bottleneck elementary reaction (or rate-determining step), whereby the constant slope (or apparent activation energy, E R app ) reflects the value of the energy barrier for that elementary reaction. In this study, we express E R app as a weighted average, where every term contains the traditional energy barrier for the corresponding elementary reaction plus an additional configurational term, while identifying each weight as the probability of executing the corresponding elementary reaction. Accordingly, the change in the leading (most probable) elementary reaction with the experimental conditions (e.g. temperature) is automatically captured and it is shown that a constant value of E R app is possible even if control shifts from one elementary reaction to another. To aid the presentation, we consider kinetic Monte Carlo simulations of submonolayer growth of Cu on Ni(111) and Ni on Cu(111) at constant deposition flux, including a large variety of single-atom, multi-atom and complete-island diffusion events. In addition to analysing the dominant contributions to the diffusion constant of the complete adparticle system (or tracer diffusivity) and its apparent activation energy as a function of both coverage and temperature for the two heteroepitaxial systems, their surface morphologies and island densities are also compared.

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Kinetic Monte Carlo Simulation of Au Monolayer Evolution on Cu(110)

Dardouri

Hassani

Hasnaoui

et al. 2018

Physica Status Solidi (b)

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In this work, results obtained from the kinetic Monte Carlo (KMC) simulations are presented. The KMC is based on embedded‐atom method (EAM) energetics findings. The evolution of the surface morphology in Au/Cu(110) is investigated. All activation barriers are calculated by the EAM method and used in the anisotropic bond‐breaking model (ABBM). In this study, the effects of substrate temperature and deposition rate are taken into account, with the coverage rate equal to 5%. The results show the transition from 1D to 2D in the morphology of the monolayer when the temperature increases. However, when the flux decreases the density of islands increases. During monolayer evolution, many phenomena are observed such as nucleation, coalescence, evolution of island density, and geometry transition.

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Diffusion of small Cu islands on the Ni(111) surface: A self-learning kinetic Monte Carlo study

Cited by 14 publications

References 59 publications

On the validity of the Arrhenius picture in two-dimensional submonolayer growth

On the validity of the Arrhenius picture in two-dimensional submonolayer growth

Dominant contributions to the apparent activation energy in two-dimensional submonolayer growth: comparison between Cu/Ni(111) and Ni/Cu(111)

Kinetic Monte Carlo Simulation of Au Monolayer Evolution on Cu(110)

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