Nonexponential decay of velocity correlations in surface diffusion: The role of interactions and ordering

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dc.contributorAalto-yliopistofi
dc.contributorAalto Universityen
dc.contributor.authorVattulainen, Ilpo
dc.contributor.authorHjelt, T.
dc.contributor.authorAla-Nissilä, Tapio
dc.contributor.authorYing, S. C.
dc.contributor.departmentDepartment of Applied Physicsen
dc.contributor.departmentTeknillisen fysiikan laitosfi
dc.contributor.schoolPerustieteiden korkeakoulufi
dc.contributor.schoolSchool of Scienceen
dc.date.accessioned2015-04-22T09:00:41Z
dc.date.available2015-04-22T09:00:41Z
dc.date.issued2000
dc.description.abstractWe study the diffusive dynamics of adparticles in two model systems with strong interactions by considering the decay of the single-particle velocity correlation functionφ(t). In accordance with previous studies, we find φ(t) to decay nonexponentially and follow a power-law φ(t)∼t−x at intermediate times t, while at long times there is a crossover to an exponential decay. We characterize the behavior of the decay exponent x in detail in various ordered phases and in the vicinity of phase boundaries. We find that within the disordered phase, the behavior of x can be rationalized in terms of interaction effects. Namely, x is typically larger than two in cases where repulsive adparticle–adparticle interactions dominate, while attractive interactions lead to x<2. In ordered phases, our results suggest that the behavior of x is mainly governed by ordering effects that determine the local structure in which adatoms diffuse. Then the decay is characterized by 1<x<2 under conditions where diffusion is truly two-dimensional, while in phases where adatoms diffuse in a one-dimensional fashion along ideal rows of vacancies, we find a regime characterized by x<1. Also, changes in the qualitative behavior of x are closely related to phase boundaries and local ordering effects. Our studies suggest that φ(t) can be used to obtain information about the ordering of the system and about the nature of predominant interactions between adparticles. Our predictions can be tested experimentally by techniques such as scanning tunneling microscopy, in which φ(t) can be measured in terms of discrete adparticle displacements as shown in this work. Finally, our studies suggest that the decay of velocity correlations in collective diffusion follows, qualitatively, the same behavior as the decay of single-particle velocity correlations in tracer diffusion.en
dc.description.versionPeer revieweden
dc.format.extent10284-10292
dc.format.mimetypeapplication/pdfen
dc.identifier.citationVattulainen, I. & Hjelt, T. & Ala-Nissilä, Tapio & Ying, S. C. 2000. Nonexponential decay of velocity correlations in surface diffusion: The role of interactions and ordering. The Journal of Chemical Physics. Volume 113, Issue 22. P. 10284-10292. ISSN 1089-7690 (electronic). ISSN 0021-9606 (printed). DOI: 10.1063/1.1322654.en
dc.identifier.doi10.1063/1.1322654
dc.identifier.issn1089-7690 (electronic)
dc.identifier.issn0021-9606 (printed)
dc.identifier.urihttps://aaltodoc.aalto.fi/handle/123456789/15745
dc.identifier.urnURN:NBN:fi:aalto-201504212378
dc.language.isoenen
dc.publisherAIP Publishingen
dc.relation.ispartofseriesThe Journal of Chemical Physicsen
dc.relation.ispartofseriesVolume 113, Issue 22
dc.rights© 2000 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. http://scitation.aip.org/content/aip/journal/jcpen
dc.rights.holderAmerican Institute of Physics
dc.subject.keyworddiffusionen
dc.subject.keywordcorrelation functionsen
dc.subject.keywordscanning tunneling microscopyen
dc.subject.keywordstrong interactionsen
dc.subject.keywordsurface dynamicsfi
dc.subject.otherPhysicsen
dc.titleNonexponential decay of velocity correlations in surface diffusion: The role of interactions and orderingen
dc.typeA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessäfi
dc.type.dcmitypetexten
dc.type.versionFinal published versionen
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