Enhanced Ab Initio Molecular Dynamics Simulation of the Temperature-Dependent Thermodynamics for the Diffusion of Carbon Monoxide on Ru(0001) Surface

Abstract

CO diffusion on the metal surface is an elementary process in many heterogeneous catalytic reactions. The thermodynamics and the molecular mechanism of the diffusion process are key factors contributing to the kinetics of the catalysis. Theoretical study based on computer simulations can complement experimental studies to provide much needed thermodynamic and mechanistic information. Here, we report direct ab initio molecular dynamics (MD) simulation to investigate the temperature-dependent thermodynamics of CO diffusion on the Ru(0001) surface combined with an efficient sampling method based on integrated tempering to speed up phase space sampling. We show that reliable and smooth two-dimensional potential of mean force surfaces of CO diffusion can be obtained at different temperatures. As expected, with increasing temperature, the distribution of CO adsorbate at different surface sites becomes more and more uniform, while the height of the free energy barrier to CO diffusion decreases. The simulation results were used to elucidate the physics of the temperature-dependent in-plane diffusion. The good agreement between the results of current simulations and previous theoretical studies demonstrates the effectiveness and reliability of free energy simulation with the enhanced ab initio molecular dynamics in heterogeneous surface processes. For complex situations where a simple harmonic model becomes inappropriate and convergent phase space sampling is required, direct MD simulation with enhanced sampling methods can make important contributions to our understanding of the thermodynamics of the surface catalytic processes.

Efficient Dynamic Computational Strategy for Heterogeneous Catalysis Based on Neural Network Potential Energy Surface: A Case Study of Temperature-Dependent Thermodynamics and Kinetics for the Chemisorbed on-surface CO

“…Our results unexpectedly showed that the relative free energy between top and hcp sites increases rather than reduces as the temperature raising, being contrary to the intuition (see Figure 2). The PMF surfaces in Figure 1 and S5 obviously suggest that the free energy curve in top site is flatter than that in hcp site, in agreement with our previous results that the frequency of the two in-plane modes is lower in the top site, 35 and further suggests the top site has less steric interactions.…”

Enhanced molecular dynamics simulation of the transformation between α-helix and β-hairpin structures for peptide

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Towardsoperandocomputational modeling in heterogeneous catalysis

“…Nevertheless, it was shown to be a suitable approach for low-energy activated processes such as carbene decomposition on a Ni(111) surface 244 or CO diffusion on a Ru(0001) surface. 243 …”