Adsorbate phase transitions on nanoclusters from nested sampling

Area of Science:

• Physical Chemistry
• Materials Science
• Computational Chemistry

Background:

• Understanding gas adsorption on nanoclusters is crucial for catalysis and materials design.
• Lennard-Jones (LJ) nanoclusters provide simplified models for studying adsorption phenomena.
• Investigating phase transitions and site selectivity is key to controlling surface interactions.

Purpose of the Study:

• To investigate adsorption equilibria on the LJ38 nanocluster using nested sampling.
• To explore the effects of adsorbate-surface well depth and LJ size parameters on adsorption behavior.
• To identify and characterize phase transitions occurring during gas adsorption.

Main Methods:

• Nested sampling simulations were performed on the truncated-octahedral LJ38 nanocluster.
• The canonical partition function was evaluated over a wide temperature range.
• Systematic variation of adsorbate-surface well depth and LJ size parameters was conducted.

Main Results:

• Two successive phase transitions were identified: gas condensation and lateral rearrangement of the adsorbed layer.
• Adsorbate-adsorbate interactions influence site preference, shifting from hollow sites to four-coordinated (100) sites when interactions weaken.
• Adsorbate size impacts low-temperature behavior, with smaller adsorbates aggregating and larger ones distributing evenly.

Conclusions:

• Nested sampling is an effective, automated tool for exploring surface configurational space.
• Findings highlight trends in facet competition and lattice mismatch in nanocluster adsorption.
• The study provides insights for designing interfaces with controlled adsorption properties.