Soft landing of metal clusters on graphite: a molecular dynamics study
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THE EUROPEAN PHYSICAL JOURNAL D
Regular Article
Soft landing of metal clusters on graphite: a molecular dynamics study? Alexey V. Verkhovtsev1,3,a , Yury Erofeev1,2 , and Andrey V. Solov’yov1,3 1 2 3
MBN Research Center, Altenh¨ oferallee 3, 60438 Frankfurt am Main, Germany Department of Physics, Utrecht University, Heidelberglaan 8, 3584 CS Utrecht, The Netherlands On leave from Ioffe Institute, Polytekhnicheskaya 26, 194021 St. Petersburg, Russia Received 7 May 2020 / Received in final form 24 August 2020 / Accepted 1 September 2020 Published online 6 October 2020 c EDP Sciences / Societ`
a Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2020 Abstract. Structure and stability of nanometer-sized Ag887 , Au887 and Ti787 clusters soft-landed on graphite (at deposition energies Edep = 0.001−5.0 eV per atom) are studied by means of molecular dynamics simulations. Parameters for the cluster–surface interactions are derived from complementary ab initio calculations. The shape and the contact angle of deposited clusters are systematically analyzed for different deposition energies and temperature regimes. The Ag887 cluster deposited at Edep . 0.1 eV/atom undergoes collision-induced plastic deformation, thus acquiring an ellipsoidal shape with the contact angle close to 180◦ . In contrast, Au887 and Ti787 clusters undergo a collision-induced melting phase transition followed by their recrystallization; these processes lead to the formation of the droplet-like shapes of the clusters in a form of truncated spheroids. At larger deposition energies all clusters flatten over the surface and eventually disintegrate at Edep ≈ 0.75−1.0 eV/atom (for Ag887 and Au887 ) and ≈3 eV/atom (for Ti787 ). It is found also that the shape of deposited clusters is strongly influenced by the strength of cluster–substrate interaction and the corresponding interaction mechanism, namely the weak van der Waals interaction between metal and carbon atoms or the van der Waals interaction with an onset of covalent bonding. Similar phenomena should arise in the deposition of clusters made of other elements, which interact with a substrate by one of the above-described mechanisms.
1 Introduction The interaction of atomic clusters and nanoparticles with surfaces has been a widely studied topic in cluster science over the past several decades [1–3]. The dynamics of metal clusters and carbon fullerenes deposited onto different surfaces (mainly, metal surfaces, graphite and silicon oxide) was explored both experimentally [4–7] and computationally by means of molecular dynamics (MD) simulations [8–10]. The strong interest in the deposition of mass-selected clusters on surfaces has been motivated by both fundamental research and technological applications. From a fundamental physics viewpoint, an important question is how structural, electronic, magnetic and optical properties of deposited clusters change with respect to free counterparts. A variety of phenomena emerge also when atomic clusters are brought in contact with a sur
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