Selection of Publications in 2015

We have selected the following articles published in 2015:

1) Our first selected study demonstrates the superfluid helium nanodroplet-mediated soft-deposition of a metallic atomic species. More specifically, an -based methodological scheme for He-surface interactions and zero-temperature time-dependent density functional theory for superfluid 4He droplets motion are combined to follow the short-time collision dynamics of the Au@4He system with the TiO(110) surface. This composite approach demonstrates the 4He droplet-assisted sticking of the metal species to the surface at low landing energy (below 0.15 eV/atom), thus providing the first theoretical evidence of the experimentally observed 4He droplet-mediated soft-landing deposition of metal nanoparticles on solid surfaces [Mozhayskiy , J. Chem. Phys. , 094701 (2007) and Loginov , J. Phys. Chem. A , 7199 (2011)].

This study was developed within the framework of our collaboration with Hermann Stoll (University of Stuttgart), Alexander O. Mitrushchenkov (Université Paris-Est), and Martí Pi (University of Barcelona).

María Pilar de Lara-Castells*, Néstor F. Aguirre, Hermann Stoll, Alexander O. Mitrushchenkov, David Mateo, and Martí Pi.

Communication: Unraveling the 4He-droplet mediated soft-landing from ab-initio-assisted and time-resolved density functional simulations

The Journal of Chemical Physics, 2015, 142 131101




2) Our second selected article presents an ab-initio study of molecular hydrogen physisorption on graphene and graphite surfaces. The interaction potential of molecular hydrogen physisorbed on a graphene sheet is evaluated using the ab initio-based periodic dlDF+Das scheme and its accuracy is assessed by comparing the nuclear bound-state energies supported by the H2(D2/HD)/graphite potentials with the experimental energies. The periodic dlDF+Das treatment uses DFT-based symmetry-adapted perturbation theory on surface cluster models to extract the dispersion contribution to the interaction whereas periodic dispersionless density functional (dlDF) calculations are performed to determine the dispersion-free counterpart. It is shown that the H2/graphene interaction is effectively two-dimensional (2D), with the distance from the molecule center-of-mass to the surface plane and the angle between the diatomic axis and the surface normal as the relevant degrees of freedom. The global potential minimum is found at the orthogonal orientation of the molecule with respect to the surface plane, with an equilibrium distance of 3.17 Å and a binding energy of −51.9 meV. The comparison of the binding energies shows an important improvement of our approach over the vdW-corrected DFT schemes when we are dealing with the very weak H2/surface interaction. Next, the 2D nuclear bound-state energies are calculated numerically. As a cross-validation of the interaction potential, the bound states are also determined for molecular hydrogen on the graphite surface (represented as an assembly of graphene sheets). With the largest absolute deviation being 1.7 meV, the theoretical and experimental energy levels compare very favorably. 

María Pilar de Lara-Castells* and Alexander O. Mitrushchenkov*

Nuclear Bound States of Molecular Hydrogen Physisorbed on Graphene: An Effective Two-Dimensional Model

Journal of Physical Chemistry A, 2015, 119, 11022-11032

3) Our third selected paper presents a a combined density functional (DFT) and incremental post-Hartree-Fock (post-HF). The approach was, proven earlier to calculate He-surface potential energy surfaces [de Lara-Castells et al., J. Chem. Phys. 141, 151102 (2014)] and, in this study, it is applied to describe the van der Waals dominated Ag2/graphene interaction. It extends the dispersionless density functional theory developed by Pernal et al. [Phys. Rev. Lett. 103, 263201 (2009)] by including periodic boundary conditions while the dispersion is parametrized via the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)]. Starting with the elementary cluster unit of the target surface (benzene), continuing through the realistic cluster model (coronene), and ending with the periodic model of the extended system, modern ab initio methodologies for intermolecular interactions as well as state-of-the-art van der Waals-corrected density functional-based approaches are put together both to assess the accuracy of the composite scheme and to better characterize the Ag2/graphene interaction. The present work illustrates how the combination of DFT and post-HF perspectives may be efficient to design simple and reliable ab initio-based schemes in extended systems for surface science applications.

This study was developed within the framework of our collaboration with Hermann Stoll (University of Stuttgart) and Alexander O. Mitrushchenkov (Université Paris-Est).

María Pilar de Lara-Castells*, Alexander O. Mitrushchenkov, and Hermann Stoll

Combining density functional and incremental post-Hartree-Fock approaches for van der Waals dominated adsorbate-surface interactions: Ag2/graphene

The Journal of Chemical Physics, 2015, 143 102804



4) The scope of our fourth selected article  is to validate the accuracy and transferability of our electronic structure approach, combining dispersionless density functional theory (DFT) [K. Pernal et al., Phys. Rev. Lett. 103, 263201 (2009)] with the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)],  for the interaction between the noble-gas Ne, Ar, Kr, and Xe atoms and coronene/graphene/graphite surfaces. This approach uses the method of increments for surface cluster models to extract intermonomer dispersion-like (2- and 3-body) correlation terms at coupled cluster singles and doubles and perturbative triples level, while periodic dispersionless density functionals calculations are performed to estimate the sum of Hartree-Fock and intramonomer correlation contributions. Dispersion energy contributions are also obtained using DFT-based symmetry-adapted perturbation theory [SAPT(DFT)]. An analysis of the structure of the X/surface (X = Ne, Ar, Kr, and Xe) interaction energies shows the excellent transferability properties of the leading intermonomer correlation contributions across the sequence of noble-gas atoms, which are also discussed using the Drude oscillator model. We further compare these results with van der Waals-(vdW)-corrected DFT-based approaches. As a test of accuracy, the energies of the low-lying nuclear bound states supported by the laterally averaged X/graphite potentials (X = 3He, 4He, Ne, Ar, Kr, and Xe) are calculated and compared with the best estimations from experimental measurements and an atom-bond potential model using the ab initio-assisted fine-tuning of semiempirical parameters. The bound-state energies determined differ by less than 6–7 meV (6%) from the atom-bond potential model. The crucial importance of including incremental 3-body dispersion-type terms is clearly demonstrated, showing that the SAPT(DFT) approach effectively account for these terms. With the deviations from the best experimental-based estimations smaller than 2.3 meV (1.9%), the accuracy of the combined DFT and post-HF incremental scheme is established for all the noble-gas atoms. With relative deviations smaller than 4% and 11%, good agreement is also achieved by applying the vdW-corrected DFT treatments PBE-D3 and vdW-DF2 for noble-gas atoms heavier than neon.

This study was developed within the framework of our collaboration with Hermann Stoll (University of Stuttgart) and Alexander O. Mitrushchenkov (Université Paris-Est), including a contribution of Massimiliano Bartolomei from our Institute of Fundamental Physics (CSIC).

María Pilar de Lara-Castells*, Massimiliano Bartolomei. Alexander O. Mitrushchenkov, and Hermann Stoll

Transferability and accuracy by combining dispersionless density functional and incremental post-Hartree-Fock theories: Noble gases adsorption on coronene/graphene/graphite surfaces

The Journal of Chemical Physics, 2015, 143 194701