Dresden 2026 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

O: Fachverband Oberflächenphysik

O 11: Metal & Semiconductor substrates: Adsorption and reaction of small molecules II

O 11.6: Talk

Monday, March 9, 2026, 16:15–16:30, HSZ/0401

Memory friction and zero-point motion in hydrogen surface diffusion — •George Trenins and Mariana Rossi — MPI for the Structure and Dynamics of Matter, Hamburg, Germany

By virtue of their small mass, hydrogen atoms readily manifest quantum dynamical effects under typical experimental conditions. In particular, hydrogen diffusion on metal surfaces is strongly influenced by nonadiabatic interactions with the conduction electrons. Such “electronic friction” is incorporated into numerical simulations via the generalized Langevin equation (GLE). Additionally, hydrogen possesses substantial zero-point energy and can undergo quantum tunnelling. This is accurately described by “ring-polymer molecular dynamics” (RPMD), an atomistic simulation approach rooted in the path-integral formulation of quantum mechanics. Using a rigorous combination of the GLE and RPMD frameworks, we show that a combination of zero-point motion and non-Markovian (memory) friction are key to the temperature dependence of H-atom diffusion on copper surfaces [1]. In a limited temperature range, the two effects happen to mask each other almost perfectly, creating the appearance of classical, memoryless dynamics. Outside this range, the experiment displays non-Arrhenius behaviour that is not captured by classical dynamics but is readily explained when quantum effects are taken into account. [1] G. Trenins, M. Rossi, Phys. Rev. Lett. 134, 226201 (2025).

Keywords: friction; path integrals; quantum dynamics; surface diffusion; non-Markovian dynamics