Intermolecular potential and second virial coefficient of the water-nitrogen complex

Area of Science:

• Computational Chemistry
• Molecular Interactions
• Physical Chemistry

Background:

• Understanding intermolecular forces is crucial for predicting the behavior of molecular systems.
• Accurate potential energy surfaces (PES) are essential for high-fidelity molecular simulations and thermodynamic property calculations.

Purpose of the Study:

• To construct a high-accuracy, five-dimensional rigid-body potential energy surface for the water-nitrogen (H2O-N2) complex.
• To determine the global minimum energy configuration and binding energy of the H2O-N2 complex.
• To calculate the second cross virial coefficient for the H2O-N2 system and compare it with experimental data.

Main Methods:

• Systematic intermolecular potential extrapolation routine used to generate the PES.
• Extrapolation to the complete basis set limit for high accuracy.
• Analytic fitting of the PES to determine the global minimum and binding energy.
• Calculation of the second cross virial coefficient using the fitted PES over a wide temperature range (100–3000 K).

Main Results:

• A global minimum energy configuration was found with N2 positioned near the H atom of H2O, nearly collinear with the OH bond.
• The best estimate for the binding energy of the H2O-N2 complex is 441 cm⁻¹.
• Calculated second cross virial coefficients show good agreement with experimental data, often with reduced uncertainties.

Conclusions:

• The developed potential energy surface provides an accurate representation of the water-nitrogen interaction.
• The study offers reliable predictions for the binding energy and thermodynamic properties of the H2O-N2 complex.
• The findings contribute to a better understanding of non-covalent interactions involving water and small molecules.