Global ab initio ground-state potential energy surface of N4

Area of Science:

• Chemical Physics
• Computational Chemistry
• Quantum Chemistry

Background:

• Accurate potential energy surfaces are crucial for simulating molecular collisions.
• Nitrogen-nitrogen (N2) interactions are fundamental in various chemical processes.

Purpose of the Study:

• To develop a global ground-state potential energy surface for the nitrogen tetroxide (N4) system.
• To enable accurate theoretical treatment of high-energy vibrational-rotational energy transfer and collision-induced dissociation in N2-N2 collisions.

Main Methods:

• Ab initio calculations using complete active space second-order perturbation theory (CASPT2).
• Employed a 12-electron, 12-orbital active space and the maug-cc-pVTZ basis set.
• Fitted approximately 17,000 data points using permutationally invariant polynomials.

Main Results:

• A global six-dimensional ground-state potential energy surface for N4 was generated.
• The surface accurately represents N2 + N2 and N3 + N geometries.
• The methodology provides a robust model for N2 collision dynamics.

Conclusions:

• The developed N4 potential energy surface is suitable for high-accuracy simulations of N2-N2 collisions.
• This work advances the understanding of energy transfer and dissociation mechanisms in nitrogen systems.
• The computational approach offers a reliable framework for future studies on related molecular interactions.