Diffusion Rates for Hydrogen on Pd(111) from Molecular Quantum Dynamics Calculations
Thiago Firmino1, Roberto Marquardt1, Fabien Gatti2
1†Laboratoire de Chimie Quantique, Institut de Chimie, UMR 7177 CNRS/Université de Strasbourg, 1 rue Blaise Pascal, BP 296/R8, 67008 Strasbourg Cedex, France.
The Journal of Physical Chemistry Letters
|August 15, 2015
Summary
This study extends the van Hove formula to account for adsorbate vibrational relaxation. Quantum effects in particle scattering are significant even at room temperature, impacting surface dynamics.
Area of Science:
- Surface science
- Condensed matter physics
- Physical chemistry
Background:
- The van Hove formula describes particle scattering at mobile adsorbates.
- Understanding adsorbate dynamics is crucial for surface science and catalysis.
Purpose of the Study:
- To extend the van Hove formula for the dynamical structure factor (DSF) to include adsorbate vibrational relaxation.
- To present a kinetic model supporting the additive nature of diffusion and relaxation rates.
- To evaluate the extended formula for H/Pd(111) using first-principle calculations.
Main Methods:
- Extension of the van Hove formula.
- Development of a simple kinetic model.
- First-principle calculations of vibrational states (wave functions, energies, lifetimes).
- Evaluation of the formula for the H/Pd(111) system.
Main Results:
- The dynamical structure factor (DSF) now incorporates adsorbate vibrational relaxation.
- A kinetic model supports the assumption that total rate is the sum of diffusion and relaxation rates.
- Calculations for H/Pd(111) show the importance of quantum effects.
Conclusions:
- The extended van Hove formula provides a more complete description of adsorbate dynamics.
- Quantum effects are significant in adsorbate vibrational relaxation, even at room temperature.
- The findings have implications for understanding surface processes and catalysis.
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