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O: Fachverband Oberflächenphysik

O 12: Surface dynamics

O 12.5: Vortrag

Montag, 26. März 2012, 17:00–17:15, H 2013

Beating the heat atomistically: Watching phonons cool down during O₂ dissociation on Pd(100) — •Jörg Meyer and Karsten Reuter — Technische Universität München, Germany

Energy conversion at interfaces is at the center of the rapidly growing field of basic energy science. One particular example is the conversion of chemical energy into heat which comes as an unavoidable by-product of all exothermic elementary reaction steps in heterogeneous catalysis. While engineers routinely deal with important consequences on a macroscopic scale based on well-known continuum theories and empirically determined effective parameters, an atomistic understanding is very limited at best. Aiming at multiscale modeling, our novel QM/Me approach extends the power of embedding techniques to metallic systems. A huge atomistically described bath can thus be included in ab initio molecular dynamics simulations of chemical reactions at catalyst surfaces. Applied to O₂ dissociation on Pd(100) as a representative showcase system, for which electron-hole pair excitations are unlikely to act as dominant primary energy dissipation channel [1], we quantify concomitant phonon excitations based on a newly developed projection scheme. Thanks to the phononic details implicitly incorporated in the bath, we obtain a high resolution for individual modes over the entire surface Brillouin zone. We can thus unravel the role of surface phonons as well as question the validity of the harmonic approximation for the solid during the dynamics – commonly employed in model Hamiltonians – from an unprecedented first-principles perspective.

[1] J. Meyer and K. Reuter, New J. Phys. 13, 085010 (2011)