One of the main challenges in theoretical gas-surface studies is to incorporate into the dynamics energy exchange to both lattice vibrations and electronic excitations, keeping the accuracy of a multidimensional ab-initio potential energy surface for describing the gas/metal interaction. In this chapter, we review some recent advances in the subject and will present a theoretical framework recently developed that allows to evaluate within a full dimensional dynamics the combined contribution of both excitation mechanisms. This objective has been accomplished by combining the Generalized Langevin Oscillator model for phonon excitations and the Local Density Friction Approximation for electronic excitations. The inclusion of both effects allows one to address such fundamental questions as which is the relative importance of phonon and electron-hole pair excitations as energy dissipation channels and to what extent the adiabatic calculation can capture the basic physics of the dynamics and provide accurate results. Results on several systems and on different elementary gas-surface processes (dissociation, scattering, and molecular adsorption) are used to enrich the discussion. We show that, even when the energy dissipated is quantitatively significant, important aspects of the scattering dynamics are well captured by the adiabatic approximation.

This work has been supported in part by the Basque Departamento de Educación, Universidades e Investigación, the University of the Basque Country UPV/EHU (Grant No. IT-366-07) and the Spanish Ministerio de Ciencia e Innovación (Grant No. FIS2010-19609-C02-02).

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