A Polarizable and Transferable PHAST N2 Potential for Use in Materials Simulation

Area of Science:

• Computational Chemistry
• Materials Science
• Chemical Physics

Background:

• Accurate modeling of molecular nitrogen (N2) is crucial for understanding heterogeneous processes.
• Existing intermolecular potentials often lack the required accuracy, speed, or transferability for complex environments.

Purpose of the Study:

• To develop a polarizable and transferable intermolecular potential energy function for N2.
• To create a model suitable for simulating heterogeneous processes, including sorption and separations.
• To ensure the potential's efficacy across gas, liquid, and solid phases of nitrogen.

Main Methods:

• Development of a five-site anisotropic model including many-body polarization.
• Parametrization using high-level electronic structure calculations (CCSD(T)/CBS).
• Inclusion of a slip-parallel dimer orientation to improve potential energy surface transferability.
• Validation through simulations of trimers, bulk phases (pressure-density isotherms), and solid phases (crystal parameters and energetics).

Main Results:

• The developed PHAST potential demonstrates high accuracy, speed, and transferability.
• Waldman-Hagler mixing rules were found to be more accurate than Lorentz-Berthelot for N2 interactions.
• The potential accurately models N2 in various environments, including metal-organic frameworks, zeolites, and interfaces.
• Simulations show good agreement with experimental data for gas, liquid, and solid N2 phases.

Conclusions:

• The PHAST potential provides a robust and broadly applicable representation of nitrogen.
• Accounting for diverse configurations, including slip-parallel orientations, is critical for transferability in heterogeneous systems.
• The developed potential is effective for modeling N2 across a wide range of conditions and applications.