Prospects for rank-reduced CCSD(T) in the context of high-accuracy thermochemistry

Abstract

Obtaining sub-chemical accuracy (1 kJ mol${}^{-1}$) for reaction energies of medium-sized gas-phase molecules is a longstanding challenge in the field of thermochemical modeling. The perturbative triples correction to CCSD, CCSD(T), constitutes an important component of all high-accuracy composite model chemistries that obtain this accuracy, but can be a roadblock in the calculation of medium to large systems due to its $\mathcal{O}(N^7)$ scaling, particularly in HEAT-like model chemistries that eschew separation of core and valance correlation. This study extends the work of Lesiuk [J. Chem. Phys. 156, 064103 (2022)] with new approximate methods and assesses the accuracy of five different approximations of (T) in the context of a subset of molecules selected from the W4-17 dataset. It is demonstrated that all of these approximate methods can achieve sub-0.1 kJ mol${}^{-1}$ accuracy with respect to canonical, density-fitted (T) contributions with a modest number of projectors. The approximation labeled $\tilde{Z}T$ appears to offer the best trade-off between cost and accuracy and shows significant promise in an order-of-magnitude reduction in the computational cost of the CCSD(T) component of high-accuracy model chemistries.

References in corpus (6)

• W4 theory for computational thermochemistry: in pursuit of confident sub-kJ/mol predictions
• W3 theory: robust computational thermochemistry in the kJ/mol accuracy range
• Basis set convergence of post-CCSD contributions to molecular atomization energies
• Implementation of the full CCSDT electronic structure model with tensor decompositions
• Tensor Hypercontraction Form of the Perturbative Triples Energy in Coupled-Cluster Theory
• A Critical Analysis of Least-Squares Tensor Hypercontraction Applied to MP3

Cited by in corpus (1)

• On the rank-reduced relativistic coupled cluster method