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