Atomic Resonant Tunneling in the Surface Diffusion of H Atoms on Pt(111)

TL;DR

This study investigates the quantum tunneling effects of hydrogen atoms on Pt(111) surfaces, revealing atomic resonant tunneling and its impact on diffusion rates at low temperatures using first-principles calculations.

Contribution

It introduces the concept of atomic resonant tunneling in surface diffusion and quantifies how quantum effects alter reaction barriers and rates at cryogenic temperatures.

Findings

Resonant tunneling causes anomalous diffusion rates at low temperatures.

Quantum tunneling significantly reduces effective energy barriers.

Reaction rates approach a nonzero limit at cryogenic temperatures.

Abstract

The quantum motions of hydrogen (H) atoms play an important role in the dynamical properties and functionalities of condensed phase materials as well as biological systems. In this work, based on the transfer matrix method and first-principles calculations, we study the dynamics of H atoms on Pt(111) surface and numerically calculate the quantum probability of H transferring across the surface potential fields. Atomic resonant tunneling (ART) is demonstrated along a number of diffusion pathways. Owing to resonant tunneling, anomalous rate of transfer is predicted for H diffusion along certain path at low temperatures.The role of nuclear quantum effects (NQEs) on the surface reactions involving H is investigated, by analyzing the probabilities of barrier-crossing. The effective barrier is significantly reduced due to quantum tunneling, and decreases monotonically with temperature within a certain region. For barrier-crossing processes where the Arrhenius type relation applies, we show the existence of a nonzero low-temperature limit of rate constant, which indicates the nontrivial activity of H-involved reactions at cryogenic conditions.