Interaction energy decomposition methods: comparison and application to covalent interaction assessment

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Interaction energy partitioning schemes are crucial for understanding non-covalent interactions.
• Basis set dependency in these schemes leads to varying component values.
• Comparing different methods against benchmark Symmetry-Adapted Perturbation Theory (SAPT) data is essential.

Purpose of the Study:

• To analyze and compare various interaction energy partitioning schemes.
• To investigate the basis set dependency of different energy components.
• To evaluate the validity of specific terms against SAPT benchmarks and assess enzyme catalysis hypotheses.

Main Methods:

• Utilized even-tempered regularized basis sets up to the Hartree-Fock limit.
• Performed Symmetry-Adapted Perturbation Theory (SAPT) calculations.
• Employed Hybrid Variation-Perturbation Theory (HVPT), Localized Molecular Orbital Energy Decomposition (LMOEDA), Kitaura-Morokuma, Reduced Variational Space (RVS), and Absolutely Localized Molecular Orbitals (ALMO) methods.

Main Results:

• HVPT delocalization and LMOEDA polarization terms closely match SAPT polarization and induction terms.
• These consistent terms rapidly saturate with increasing basis set size.
• Kitaura-Morokuma, RVS, and ALMO charge-transfer terms exhibit significant basis set dependency and vanish in the large-basis-set limit.

Conclusions:

• HVPT and LMOEDA provide reliable energy components comparable to SAPT.
• Basis set choice critically impacts charge-transfer terms in KM, RVS, and ALMO methods.
• The ratio of delocalization to electrostatic terms can quantitatively assess covalent interactions in enzyme active sites.