Regional Embedding Enables High-Level Quantum Chemistry for Surface Science.

Area of Science:

• Computational chemistry
• Materials science
• Quantum mechanics

Background:

• Ab initio wave function methods offer high accuracy for modeling materials.
• Correlated wave function methods are computationally expensive for large systems like periodic materials.
• Modeling adsorbates and defects in periodic systems requires accurate electronic structure calculations.

Purpose of the Study:

• To develop a computationally efficient method for accurate modeling of adsorbates and defects in periodic systems.
• To enable the application of correlated wave function methods to localized regions of interest.
• To reduce the computational cost associated with modeling large periodic systems.

Main Methods:

• Introduction of the regional embedding approach.
• Construction of small, fragment-localized orbital spaces using a simple overlap criterion.
• Application of correlated wave function treatments to a target fragment.

Main Results:

• Demonstrated successful application to water adsorption on lithium hydride, hexagonal boron nitride, and graphene.
• Achieved converged CCSD(T) (coupled-cluster) adsorption energies.
• Showcased accuracy with very small fragment sizes.

Conclusions:

• The regional embedding approach provides a computationally feasible alternative to large supercells for correlated wave function methods.
• This method enables accurate modeling of adsorbates and defects in periodic systems.
• Regional embedding combined with focal-point corrections offers a reliable approach for calculating adsorption energies.