Potential energy surface for high-energy N + N₂ collisions.

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Atmospheric Chemistry

Background:

• Potential energy surface (PES) calculations are vital for understanding molecular collisions and energy transfer.
• Accurate PES for nitrogen species are needed for modeling high-energy phenomena like atmospheric shock waves.

Purpose of the Study:

• To present an analytic ground-state potential energy surface for nitrogen triatomics (N3).
• To describe electronically adiabatic collisions between nitrogen molecules (N2) and nitrogen atoms (N).

Main Methods:

• Developed a pairwise potential combined with a three-body term using permutationally invariant polynomials (PIP).
• Utilized multireference complete active space second order perturbation theory (CASPT2) for fitting the three-body interactions.
• Analyzed reaction paths, local minima, transition structures, and van der Waals geometries.

Main Results:

• An accurate analytic ground-state (4A") PES for N3 was generated.
• Characterized key topographical features including minima, transition states, and van der Waals complexes.
• Identified that collinear N + N2 collisions facilitate more efficient vibrational energy transfer than perpendicular approaches.

Conclusions:

• The developed N3 PES provides a robust tool for simulating chemical dynamics in atmospheric shock waves.
• Collision geometry significantly impacts energy transfer efficiency, with collinear approaches being more favorable.