Nos études portent sur la dynamique et la réactivité des atomes et des molécules en phase gazeuse ou en interaction avec des surfaces. Notre objectif est d’obtenir des probabilités de réaction, de déterminer la répartition de l’énergie entre la surface, le mouvement de translation et les degrés de liberté internes des produits, de caractériser l’effet de surface sur les réactions chimiques. Ces études sont développées dans le contexte des nanosciences.

Dissipative friction dynamics within the density-functional based tight-binding scheme

The accurate description of an atom or molecule colliding with a metal surface remains challenging. Several strategies have been performed over the past decades to include in a Langevin dynamics the energy transfer related to electron–hole pair excitations in a phenomenological way through a friction contribution. We report the adaptation of two schemes previously developed in the literature to couple the electronic friction dynamics with the density-functional based tight-binding (DFTB) approach. The first scheme relies on an electronic isotropic friction coefficient determined from the local electronic density (local density friction approximation or LDFA). In the second one, a tensorial friction is generated from the non-adiabatic couplings of the ground electronic state with the single electron–hole excitations (electron tensor friction approximation or ETFA). New DFTB parameterization provides potential energy curves in good agreement with first-principle density-functional theory (DFT) energy calculations for selected pathways of hydrogen atom adsorbing onto the (100) silver surface or penetrating subsurface. Preliminary DFTB/Langevin dynamics simulations are presented for hydrogen atom scattering from the (100) silver surface and energy loss timescales are characterized.

Article: Eric Michoulier, Didier Lemoine, Fernand Spiegelman, Sven Nave, Mathias Rapacioli, « Dissipative friction dynamics within the density-functional based tight-binding scheme », Eur. Phys. J. Spec. Top. 232, 1975–1983 (2023)