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DTSTAMP:20260412T232814
DTSTART:20161114T113000
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URL:https://murmitoyen.com/events/vanille/udem/detail/713809-metallic-nanop
 articles-deposited-on-extended-graphitic-substrates-coarse-graining-approa
 ch-for-dispersion-forces-daniel-forster-udem
LOCATION:Université de Montréal - Pavillon J.-Armand-Bombardier\, 5155\, 
 chemin de la rampe \, Montréal\, QC\, Canada\, H3T 2B2
SUMMARY:Metallic nanoparticles deposited on extended graphitic substrates: 
 Coarse-graining approach for dispersion forces - Daniel Forster (UdeM)
DESCRIPTION:Daniel Forster\, département de physique\, UdeMchercheur postd
 octoral dans le groupe de Laurent Lewis
\nAbstract:
\nGraphene\, graphite 
 or epitaxial graphene on metal as a substrate for nanoparticle deposition 
 have recently become an active field of experimental and theoretical resea
 rch [1\, 2]. In particular\, epitaxial graphene on metal forms moiré stru
 ctures due to incommensurate lattice constants favoring self-assembly of a
 dsorbates. In this work\, we consider weakly interacting platinum nanoclus
 ters [3] on these substrates and compare them to more strongly bound ruthe
 nium adsorbates [4].
\nIn order to study the dynamical properties of such 
 systems of reasonable size (up to thousands of atoms)\, we employed a semi
 -empirical bond-order potential [5]. However this type of potential lacks 
 the contribution of long-range London dispersion forces which affect the b
 ehavior of the adsorbates significantly due to the semi-infinite nature of
  the substrate. We address this issue by extending the covalent force fiel
 d by the empirical Grimme D2 dispersion correction commonly used in combin
 ation with electronic structure calculations [6]. In a coarse-grained appr
 oach we have integrated the contribution of entire substrate layers to the
  dispersion forces. Non-additivity of dispersion forces involving the meta
 l part of the substrate is taken into account via an empirical screening f
 actor.
\nThrough local optimizations\, we studied the influence of the dis
 persion description on the structure and stability of defective graphene o
 n metal as well as nanoclusters deposited on the different substrates. At 
 finite temperature molecular dynamics simulations shed light on the surfac
 e diffusion mechanism of the adsorbates. Further the analysis of vibration
 al properties of the different subsystems gives insight into anharmoniciti
 es. Throughout these computations the effect of the explicit and implicit 
 dispersion description is always evaluated. Validation against available e
 xperimental [7] and ab-initio [8] results is attempted.
\n[1] J. Wintterli
 n. and M.-L. Bocquet\, Surf. Sci. 603\, 1841 (2009).[2] H. Tetlow\, J. Pos
 thuma de Boer\, I. J. Ford\, D. D. Vvedensky\, J. Coraux\, and L. Kantorov
 ich\, Phys. Rep. 542\, 195 (2014).[3] G. D. Förster\, F. Rabilloud\, and 
 F. Calvo\, Phys. Rev. B 91\, 245433 (2015).[4] G. D. Förster\, F. Rabillo
 ud\, and F. Calvo. Phys. Rev. B 92\, 165425 (2015).[5] D. W. Brenner\, Phy
 s. Rev. B 42\, 9458 (1990).[6] S. Grimme\, J. Antony\, S. Ehrlich\, and H.
  Krieg\, J. Chem. Phys. 132\, 154104 (2010).[7] M. Gao\, Y. Pan\, L. Huang
 \, H. Hu\, L. Z. Zhang\, H. M. Guo\, S. X. Du\, and H.-J. Gao\, Appl. Phys
 . Lett. 98\, 033101 (2011).[8] G. Ramos-Sanchez and P. B. Balbuena\, Phys.
  Chem. Chem. Phys. 15\, 11950 (2013).
\n 
\nCette conférence est présen
 tée par le RQMP Versant Nord du Département de physique de l'Universit
 é de Montréal et le Département de génie physique de Polytechnique M
 ontréal.
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