Incoherent tunneling surface diffusion

Area of Science:

• Surface Science
• Quantum Mechanics
• Chemical Physics

Background:

• Transition State Theory (TST) struggles with accurate friction coefficients for adsorbate diffusion.
• Understanding hydrogen and deuterium diffusion on metal surfaces like Pt(111) is crucial for catalysis.
• Incoherent tunneling is a key quantum effect in surface diffusion at low temperatures.

Purpose of the Study:

• To analyze incoherent tunneling surface diffusion using the stochastic wave function (SWF) method.
• To accurately calculate diffusion rates for H and D adsorbates on Pt(111).
• To investigate the transition between thermal activation and quantum tunneling regimes.

Main Methods:

• Stochastic Wave Function (SWF) method within the Lindblad formalism.
• Analysis across a range of surface temperatures to cover thermal activation and tunneling.
• Utilized estimated physical parameters from the thermal activation regime without fitting.

Main Results:

• Achieved good agreement between calculated and experimental hopping/tunneling rates for H and D on Pt(111).
• Successfully modeled the cross-over temperature between diffusion regimes.
• Provided estimations for friction coefficients, well/barrier frequencies, and barrier height.

Conclusions:

• The SWF method provides a robust framework for studying surface diffusion, overcoming TST limitations.
• Accurate prediction of diffusion rates is possible by incorporating quantum tunneling effects.
• The study offers insights into adsorbate dynamics on metal surfaces relevant to surface chemistry.