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Oihana Galparsoro

Publications and source records attributed to Oihana Galparsoro.

3 recordsLinked to original sources

Quantum Dynamical and isotopic effects for Hydrogen isotopes scattering at W(110) surface

We investigate the scattering of hydrogen isotopes at the W(110) surface using both classical and quantum dynamics approaches to elucidate the role of quantum effects in this system. To characterize the scattering process we focus on key observables, including the absorption probability and diffraction channels that we evaluate at the quasi-classical and quantum levels. The quantum dynamics reveal pronounced resonance structures in the absorption curve that we rationalize in terms of diffraction-mediated selective adsorption and focused sticking mechanisms. Diffraction probabilities for reflected trajectories exhibit strong quantum effects at low incident energies, where classical dynamics underestimate the back scattering probability. These effects become less pronounced with increasing isotope mass, from hydrogen to tritium, however discrepancies between the classical and quantum description persist at low incident energies.

physics.chem-ph↗

Hydrogen abstraction from metal surfaces: When electron-hole pair excitations strongly affect hot-atom recombination

Using molecular dynamics simulations, we predict that the inclusion of nonadiabatic electronic excitations influences the dynamics of preadsorbed hydrogen abstraction from the W(110) surface by hydrogen scattering. The hot-atom recombination, which involves hyperthermal diffusion of the impinging atom on the surface, is significantly affected by the dissipation of energy mediated by electron-hole pair excitations at low coverage and low incidence energy. This issue is of importance as this abstraction mechanism is thought to largely contribute to molecular hydrogen formation from metal surfaces.

cond-mat.mtrl-sci↗

The random force in molecular dynamics with electronic friction

The Langevin equation includes a random force to maintain equilibrium and prevent friction from bringing motion to a standstill; but for ballistic motion, the random force is often neglected. Here, we use the Langevin equation for molecular dynamics simulations of 2.76 eV H-atoms experiencing electronic friction in collisions with 300 K metals, where a random force arises from thermal electron-hole pairs. Simulations without the random force fail dramatically to reproduce experiment, although the incidence energy is much larger than $k_\text{B}T$. We analyze the Ornstein-Uhlenbeck process to show that this is a general property of ballistic particles experiencing friction under the influence of thermal fluctuations.

cond-mat.stat-mech↗