Highly accurate potential energy surface for the He-H2 dimer

Area of Science:

• Physical Chemistry
• Atomic and Molecular Physics
• Quantum Chemistry

Background:

• Accurate interaction potentials are crucial for understanding van der Waals complexes.
• Previous potentials for He-H2 may lack the precision for certain quantum calculations.

Purpose of the Study:

• To develop a highly accurate interaction potential for the He-H2 van der Waals complex.
• To reparameterize an existing potential surface for broader applicability.
• To compute bound state properties and virial coefficients for He-H2 systems.

Main Methods:

• Ab initio energy calculations using coupled-cluster methods with large basis sets.
• Inclusion of higher-order excitation and diagonal Born-Oppenheimer corrections.
• Reparameterization of the Boothroyd-Martin-Peterson potential surface.

Main Results:

• A new 3D potential for the He-H2 van der Waals region was constructed.
• The new potential's well depth is 15.870 ± 0.065 K, exceeding previous studies.
• Properties of bound states for (4)He-H2 and (3)He-H2, and the second virial coefficient were computed.

Conclusions:

• The developed potential offers improved accuracy for He-H2 interactions.
• The reparameterized potential is suitable for all configurations of the triatomic system.
• Accurate calculations of He-H2 properties are now feasible with the new potential.