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Hydrogen molecules can be trapped in the nanocavity formed by the tip of a scanning tunneling microscope and a metal or molecular surface, and produce sharp inelastic non-linearities in the tunneling spectra. Here, we study the interaction effects of hydrogen in a tunneling junction created over Manganese phthalocyanines molecules in two oxidation states. The effect of hydrogen in the tunneling spectra varies strongly depending on the molecular species, but its force spectrum is fairly independent on the molecular state. We find that in mild tunneling conditions hydrogen-induced forces are weakly attractive during a small range of tip sample distance. The van der Waals interaction shows a maximum value of 140 pN, which faintly depends on electrostatic variations along the surface. These results show that AFM can be employed to resolve the complex interaction landscape of a trapped hydrogen molecule and deduce fainter effects such as molecular deformations or dipolar fields., The research was financially supported by the Spanish Ministerio de Economia y Competitividad, MINECO (Grant FIS 2015-62538-ERC, MAT2016-78293-C6, and the Maria de Maeztu Units of Excellence Programme MDM-2016-0618), the Basque Government (Departamento de Industria, grant no. PI-2015-1-42, and Departamento de Educación and UPV/EHU, grant No. IT-756-13), and the European Regional Development Fund (ERDF).

26th International Conference on Atomic Collisions in Solids, A method is presented to compute the dielectric function for extended systems using linear response time-dependent density functional theory. Localized basis functions with finite support are used to expand both eigenstates and response functions. The electron-energy loss function is directly obtained by an iterative Krylov-subspace method. We apply our method to graphene and silicon and compare it to plane-wave based approaches. Finally, we compute electron-energy loss spectrum of C60 crystal to demonstrate the merits of the method for molecular crystals, where it will be most competitive., We acknowledge support from ANR OrgaVolt project. D.S-P. and P.K. acknowledge support from the Basque Departamento de Educación, UPV/EHU (Grant No. IT-366-07), the Spanish Ministerio de Ciencia e Innovación (Grant No. FIS2010-19609-C02-02), the ETORTEK program funded by the Basque Departamento de Industria and the Diputación Foral de Guipuzcoa. D.S-P., P.K. and M.P.L. acknowledge the German DFG through SFB 1083.

Using time-dependent density functional theory we calculate from first-principles the rate of energy transfer from a moving charged particle to the electrons in an insulating material. The behavior of the electronic stopping power in LiF (a wide band gap insulator) versus projectile velocity displays an effective threshold velocity of 8.2 Bohr/asec for the proton, consistent with recent experimental observations. The calculated proton/antiproton stopping power ratio is 2.4 at velocities slightly above the threshold (16.5 Bohr/asec) as compared to the experimental value of 2.1. The approximations introduced in this new non-perturbative methodology are discussed, and results on the velocity dependence of the stopping power, the locality of the energy transfer, and other characteristics of the host material are presented., This work has been funded by the EC’s Marie Curie program, UK’s BNFL and NERC, the Spanish MEC, the UPV/EHU and the Basque Government through the Etortek program.

The decay rates of electron and hole excitations at metal surfaces as determined by a scanning tunnelling microscope are presented and discussed. Surface-localised electron states as diverse as Shockley-type surface states and quantum well states confined to ultrathin alkali metal adsorption layers are covered. Recent developments in the analysis of the experimental procedures that are used to determine decay rates with the scanning tunnelling microscope, namely the analysis of line shapes and the spatial decay of standing wave patterns, are discussed., Financial support by the Deutsche Forschungsgemeinschaft and the British Council is gratefully acknowledged. This work has been supported by the Basque Departamento de Educación, the UPV/EHU, the Spanish Ministerio de Educación y Ciencia, the European Network of Excellence FP6-NoE NANOQUANTA, and the projects NANOMATERIALES and NANOTRON funded by the Basque Departamento de Industria, Comercio y Turismo within the ETORTEK programme and the Departamento para la Innovación y la Sociedad del Conocimiento from the Diputación Foral de Guipúzcoa.

arXiv:cond-mat/0512618v1, Using X-ray diffraction Ghose et al. [S.K. Ghose, I.K. Robinson, P.A. Bennett, F.J. Himpsel, Surf. Sci. 581 (2005) 199] have recently produced a structural model for the quantum-wire surface Si(5 5 3)–Au. This model presents two parallel gold wires located at the step edge. Thus, the structure and the gold coverage are quite different from previous proposals. We present here an ab initio study using density functional theory of the stability, electronic band structure and scanning tunneling microscopy images of this model., This work was supported by the Basque Departamento de Educación, the UPV/EHU (Grant No. 9/UPV 00206.215-13639/2001), the Spanish Ministerio de Educacón y Ciencia (Grant No. FIS2004-06490-C3-02), and the European Network of Excellence FP6-NoE “NANOQUANTA” (500198-2). SR also acknowledges support from the Magnus Ehrnroot Foundation.

A calculation of the inelastic scattering rate of Xe atoms on Cu(111) is presented. We focus on the regimes of low and intermediate velocities, where the energy loss is mainly associated to the excitation of electron–hole pairs in the substrate. We consider trajectories parallel to the surface and restrict ourselves to the Van der Waals contribution. The decay rate is calculated within a self-energy formulation. The effect of the response function of the substrate is studied by comparing the results obtained with two different approaches: the specular reflection model and the random phase approximation. In the latter, the surface is described by a finite slab and the wave functions are obtained from a one-dimensional model potential that describes the main features of the surface electronic structure while correctly retains the image-like asymptotic behaviour. We have also studied the influence of the surface state on the calculation, finding that it represents around 50% of the total probability of electron–hole pairs excitation., This work has been partially funded by the University of the Basque Country under Grant UPV/EHU (9/UPV 00206.215-13639/2001) and Spanish MCyT under Grant (MAT2001-0946). D.S.P. acknowledges support from Spanish CSIC and MCyT under the ‘Ramón y Cajal’ programme.

The adsorption of C60 on Si(111) has been studied by means of first-principles density functional calculations. A 2x2 adatom surface reconstruction was used to simulate the terraces of the 7x7 reconstruction. The structure of several possible adsorption configurations was optimized using the ab initio atomic forces, finding good candidates for two different adsorption states observed experimentally. While the C60 molecule remains closely spherical, the silicon substrate appears quite soft, especially the adatoms, which move substantially to form extra C-Si bonds, at the expense of breaking Si-Si bonds. The structural relaxation has a much larger effect on the adsorption energies, which strongly depend on the adsorption configuration, than on the charge transfer., 4 pages with 3 postscript figures, to appear in Surf. Science. (proceedings of the European Conference on Surface Science ECOSS-19, Sept 2000)

We present results on a well known system, C60 on Si(111)(7×7), which show that the scanning tunneling microscope (STM) is probing a single molecular orbital (MO). This MO, after comparison of experimental intramolecular structure with ab initio calculations, arises from the highest occupied MO (HOMO). The adsorbed molecules keep their relevant electronic identity but suffer a decrease in their icosahedral symmetry. The nature of the chemical bonding is proposed as being responsible for selecting one single MO in the imaging mechanisms. Our results represent an example of a strongly interacting system that can be interpreted with a great level of detail, overcoming substrate complexities., We acknowledge financial support from Spain's DGES. DSP acknowledges support from grants DOE8371494 and DEFG02/96/ER 45439.