The S66 Noncovalent Interaction Benchmark Re-examined: Composite Localized Coupled Cluster Approaches

TL;DR

This paper re-examines the S66 noncovalent interaction benchmark using localized coupled-cluster methods, demonstrating that small basis set calculations with additivity corrections can reliably approximate high-level reference energies.

Contribution

It introduces composite LNO-CCSD(T) schemes that achieve high accuracy with reduced computational cost for noncovalent interactions.

Findings

Composite schemes have RMS deviations ≤ 0.05 kcal/mol from reference energies.

Counterpoise corrections are not significantly impactful on the composite results.

Small basis set calculations with additivity corrections are sufficient for accurate interaction energies.

Abstract

The S66 non-covalent interactions are studied through localized coupled-cluster methods and general LNO-CCSD(T)-based composite schemes. Very small RMS deviations (\leq 0.05 kcal/mol) for the low-cost composite approaches from the SILVER reference interaction energies of S66 indicate that we can safely avoid carrying out the largest basis set calculations with veryVeryTight thresholds, and apply instead additivity corrections in smaller basis sets. Interestingly, the counterpoise corrections do not have an appreciable effect on the composite schemes. These findings may prove useful for intermolecular and intramolecular NCIs of larger systems.