Interaction of dihydrogen with small and light molecules

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Interactions

Background:

• Understanding molecular hydrogen interactions is crucial for catalysis and materials science.
• Accurate prediction of binding energies requires advanced theoretical methods.

Purpose of the Study:

• To investigate the interaction energies of molecular hydrogen (H2) with small molecules (HF, H2O, NH3, LiOH).
• To determine the preferred adsorption configurations of H2 on these molecules.
• To assess the impact of computational methods and basis sets on interaction energy calculations.

Main Methods:

• Second-order Møller-Plesset (MP2) calculations, including RI-MP2 and MP2-R12.
• Coupled-cluster calculations [CCSD(T)] with perturbative triples.
• Exploration of various adsorption sites and molecular orientations.

Main Results:

• Favorable H2 adsorption on H2O and NH3 occurs in an end-on fashion at O or N atoms.
• H2 adopts a side-on position on the H atom of HF or the Li atom of LiOH.
• Basis set enlargement and advanced correlation treatments (CCSD(T)) significantly increase interaction energies.
• Basis set limit CCSD(T) interaction energies: HF (4.40), H2O (2.67), NH3 (3.02), LiOH (10.74) kJ mol-1.
• H2 interaction with glycine, glycine dimer, and imidazolium chloride were also calculated.

Conclusions:

• CCSD(T) calculations provide accurate interaction energies for H2 with small molecules.
• The choice of computational method and basis set is critical for reliable results.
• Specific adsorption geometries and energies were identified for H2-molecule interactions.