Second Virial Coefficients for N₂···H₂ and NH···NH

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Chemical Physics

Background:

• Accurate thermodynamic properties of real gases are crucial for various scientific and industrial applications.
• Realistic intermolecular potential energy surfaces are essential for describing gas behavior beyond the ideal gas approximation.
• The second virial coefficient (B(T)) provides a first-order correction to the ideal gas equation of state.

Purpose of the Study:

• To introduce a first-order correction to the ideal gas equation of state by computing the classical second virial coefficient, B(T).
• To utilize the double many-body expansion (DMBE) potential energy surface for the N2H2 system to derive pairwise interaction potentials.
• To compute thermodynamic properties, including B(T), compressibility factors, and heat capacities, for H2···N2 and NH···NH systems.

Main Methods:

• Computation of the classical second virial coefficient (B(T)) from the configurational partition function, dependent on intermolecular interaction potentials.
• Application of the double many-body expansion (DMBE) potential energy surface for the ground electronic state of the N2H2 system.
• Numerical evaluation of the canonical partition function using derived pairwise interaction potentials for H2···N2 and NH···NH.

Main Results:

• Pairwise interaction potentials for H2···N2 and NH···NH were derived from the DMBE potential energy surface.
• Second virial coefficients (B(T)) were computed for H2···N2 and NH···NH systems in the temperature range of 30-2000 K.
• Calculated B(T) values for H2···N2 showed good agreement with existing literature data, while NH···NH results aligned with expected trends for similar systems.

Conclusions:

• The study successfully computed the second virial coefficient and other thermodynamic properties for real gas systems using realistic intermolecular potentials.
• The DMBE potential energy surface proved effective in deriving interaction potentials for accurate thermodynamic calculations.
• The findings contribute to a better understanding of real gas behavior and provide valuable data for the H2···N2 and NH···NH systems.