Pursuing the basis set limit of CCSD(T) non-covalent interaction energies for medium-sized complexes: case study on the S66 compilation

Abstract

Our recently developed conventional, explicitly correlated, and local natural orbital (LNO) based coupled cluster with single, double, and perturbative triple excitations [CCSD(T)] methods are utilised to closely approach the basis set limit of interaction energies between medium-sized molecular complexes. The study is partly motivated by our previous finding that state-of-the-art diffusion Monte Carlo and CCSD(T) interaction energies are not in complete agreement even for some of the dimers in the popular S66 compilation [Al-Hamdani and Nagy et al. Nat. Commun. (2021) 12:3927]. We improve upon the previous S66 CCSD(T) reference by using up to the quadruple-ζ (QZ) level CCSD(T) contributions, utilising our recent (T+) approach and suggesting a more robust explicitly correlated CCSD reference. Our efficient LNO-CCSD(T) method allowed us to also compute tightly converged, quintuple-ζ level interaction energies for the S66 set. Moreover, the new CCSD(T)/QZ references enabled the so far most rigorous benchmark of the LNO and other popular local correlation approaches on the S66 set. The accuracy of local approximations was found in the few 10 to few 100 cal/mol interaction energy error range, assuming sufficiently tight settings, such as the Tight and the Normal settings of LNO-CCSD(T) threshold combinations, respectively.

GRAPHICAL ABSTRACT

Keywords:

• Non-covalent interactions
• coupled-cluster theory
• CCSD(T)
• local and explicit correlation methods

Acknowledgments

This paper is dedicated to Professor Péter G. Szalay on the happy occasion of his 60th birthday. The authors wish to express their gratitude to Péter for the fruitful scientific collaborations and support.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Tabulated data plotted in Figures 1 and 2 for the CCSD and (T) interaction energies of (AcOH)${}_2$. The (T) IE contributions of CCSD(F12*)(T) for all S66 dimers analogously to the bottom panel of Figure 4. Moreover, s66$\mathrm{\_}$14kGOLD.xls contains the new 14k-GOLD reference values and all the new benchmark data computed at the CCSD(T)/haXZ (X= T, Q) and CCSD(F12*)(T)/haXZ-F12 (X= D, T) level of theory.

Additional information

Funding

The authors are grateful for the financial support from the National Research, Development, and Innovation Office (NKFIH, Grant No. KKP126451). The research reported in this paper is part of project BME-EGA-02, implemented with the support provided by the Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund, financed under the TKP2021 funding scheme. The computing time granted on the Hungarian HPC Infrastructure at NIIF Institute, Hungary, and DECI resources Kay with support from the PRACE aisbl are gratefully acknowledged.