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Compressed representation of dispersion interactions and long-range electronic correlations
Jérôme F Gonthier1, Martin Head-Gordon1
1Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, California 94720, USA and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
The Journal of Chemical Physics
|October 17, 2017
Summary
Researchers developed a compressed representation for electron correlation, specifically focusing on dispersion interactions. This method accurately describes dispersion energies using localized occupied-virtual geminal pairs, simplifying calculations for larger systems.
Area of Science:
- Quantum Chemistry
- Computational Chemistry
- Theoretical Chemistry
Background:
- Accurate quantum chemical calculations often require complex multi-index representations of electron correlation.
- Dispersion interactions, crucial for describing van der Waals forces, are a significant component of electron correlation.
- Existing methods for electron correlation can be computationally expensive, especially for larger molecular systems.
Purpose of the Study:
- To investigate a compressed representation for the long-range part of electron correlation, specifically targeting dispersion interactions.
- To develop a more efficient and accurate method for calculating dispersion energies in quantum chemistry.
- To explore the connection between compressed representations and the physical origins of dispersion.
Main Methods:
- Coupled-cluster singles and doubles (CCSD) computations were performed using localized orbitals.
- The portion of CCSD amplitudes corresponding to dispersion energies was extracted.
- Singular value decomposition (SVD) was employed to compress the representation of these amplitudes and analyze virtual orbitals.
Main Results:
- A highly compressed representation of dispersion energy amplitudes was achieved using occupied-virtual geminal pairs on each monomer.
- These geminals accurately describe dispersion energies at medium and long distances.
- The virtual orbitals associated with these geminals were linked to the multipole expansion of dispersion energies, demonstrating robustness across basis sets and system sizes (e.g., benzene-methane dimer).
Conclusions:
- A compressed, localized geminal-based representation provides an accurate description of dispersion interactions.
- This approach simplifies the treatment of electron correlation, particularly for dispersion energies.
- The findings enable practical and accurate approximations for dispersion, beneficial for local correlation methods and large-scale computations.
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