Helium mediated deposition: Modeling the He−TiO₂(110)-(1×1) interaction potential and application to the collision of a helium droplet from density functional calculations

Abstract

This paper is the first of a two-part series dealing with quantum-mechanical (density-functionalbased) studies of helium-mediated deposition of catalytic species on the rutile TiO 2 (110)-(1×1) surface. The interaction of helium with the TiO 2 (110)-(1×1) surface is first evaluated using the Perdew-Burke-Ernzerhof functional at a numerical grid dense enough to build an analytical three-dimensional potential energy surface. Three (two prototype) potential models for the He-surface interaction in helium scattering calculations are analyzed to build the analytical potential energy surface: (1) the hard-corrugated-wall potential model; (2) the corrugated-Morse potential model; and (3) the threedimensional Morse potential model. Different model potentials are then used to study the dynamics upon collision of a 4 He 300 cluster with the TiO 2 (110) surface at zero temperature within the framework of a time-dependent density-functional approach for the quantum fluid [D. Mateo, D. Jin, M. Barranco, and M. Pi, J. Chem. Phys. 134, 044507 (2011)] and classical dynamics calculations. The laterally averaged density functional theory-based potential with an added long-range dispersion interaction term is further applied. At variance with classical dynamics calculations, showing helium droplet splashing out of the surface at impact, the time evolution of the macroscopic helium wavefunction predicts that the helium droplet spreads on the rutile surface and leads to the formation of a thin film above the substrate. This work thus provides a basis for simulating helium mediated deposition of metallic clusters embedded within helium nanodroplets.

Assessing the Performance of Dispersionless and Dispersion-Accounting Methods: Helium Interaction with Cluster Models of the TiO2(110) Surface

“…58 This approach is justified by the fact that only minor surface ion displacements upon helium physisorption were observed (0.0013Å as much). 3 The cluster of stoichiometry (…”

“…The interest on the He-surface interaction problem has been renewed after the appearance of the helium droplet mediated deposition technique as an experimental tool for the cold attachment of embedded molecules and clusters on surfaces. 2 The microscopic understanding of this process requires quantum dynamical simulations, 3 using realistic He-surface interaction potentials.…”

“…Both as a technological relevant surface [4][5][6] and a prototype transition metal-oxide substrate with well-characterized properties, 4 we have chosen the perfect rutile TiO 2 (110)-(1×1) surface. 3,7 Naturally, cost-efficient calculations of He-surface interaction potentials should use standard periodic electronic structure codes (e.g., CRYSTAL 8 and VASP 9 ), in which methods based on density functional theory (DFT), and Hartree-Fock (HF) or hybrid HF/DFT approaches are implemented using either localized atom-centered Gaussian-type orbitals or plane-wavebased one-electron basis sets. Since these methods are not appropriate to describe the long-range correlation effects in weakly bound systems, the inclusion of long-range dispersive corrections (referred to as +D corrections) has become one of the current standards in DFT-based calculations when physisorption problems are addressed (for e recent review, see Ref.…”

Unusual behavior in magnesium-copper cluster matter produced by helium droplet mediated deposition

“…Recent models of the landing process suggest that the helium droplet does not "splash" during impact, but instead spreads out due to quantum mechanical effects; a mechanism that may serve to reduce contributions to the surface diffusion of clusters. 29 Additional efforts by Thaler et al, utilizing molecular dynamics simulations, demonstrated the stability of large silver clusters on surfaces after a low-energy ballistic landing. 30 Figure 2 shows the elemental mapping of representative Mg/Cu clusters deposited on a TEM grid.…”

Synthesis of nanoparticles in helium droplets—A characterization comparing mass-spectra and electron microscopy data

“…[18][19][20] Transmission electron microscopy (TEM) is a powerful tool for the characterization of deposited nanoparticles. The availability of aberration corrected microscopes, operating in a scanning mode (STEM), as well as very thin substrates enables the imaging of very small particles with atomic resolution.…”