N(2)O in small para-hydrogen clusters: Structures and energetics

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Molecular Physics

Background:

• Nitrous oxide (N2O) is a linear molecule with significant environmental and industrial relevance.
• Understanding the behavior of N2O in clusters with other molecules, like para-hydrogen (p-H2), is crucial for predicting its properties in various states.
• Para-hydrogen (p-H2) is the spin isomer of molecular hydrogen, exhibiting unique quantum properties.

Purpose of the Study:

• To determine the minimum-energy structures and energetics of N2O-(p-H2)n clusters.
• To investigate the solvation shell formation around the N2O molecule by p-H2.
• To compare computational findings with available experimental data.

Main Methods:

• Utilized pairwise additive potentials to model interactions between N2O and p-H2 molecules.
• Calculated interaction energies by averaging full-dimensional potentials over H2 angular coordinates.
• Employed a Genetic Algorithm for optimizing the minimum-energy structures of the clusters.

Main Results:

• Identified three stable configurations for the averaged (p-H2)-N2O potential: T-shaped, linear (p-H2)-ONN, and linear (p-H2)-NNO.
• Observed that p-H2 molecules arrange in three solvation rings around the N2O axis, with up to five molecules per ring.
• Determined that the first solvation shell is complete with 17 p-H2 molecules.
• Noted oscillations in chemical potential with cluster size up to the completion of the first solvation shell.

Conclusions:

• The study successfully modeled the structure and energetics of N2O-(p-H2)n clusters.
• The findings on solvation shell completion and chemical potential behavior align with experimental observations.
• Provides a detailed molecular-level understanding of N2O-p-H2 interactions.