W4$Î$: leveraging $Î$ coupled cluster for accurate computational thermochemistry approaches

Emmanouil Semidalas; Amir Karton; Jan M. L. Martin

doi:10.1021/acs.jpca.3c08158

paper

W4 $I^$ : leveraging $I^$ coupled cluster for accurate computational thermochemistry approaches

arXiv:2312.09062 · doi:10.1021/acs.jpca.3c08158

Abstract

High-accuracy composite wavefunction methods like Weizmann-4 (W4) theory, high-accuracy extrapolated \textit{ab initio} thermochemistry (HEAT), and Feller-Peterson-Dixon (FPD) enable sub-kJ/mol accuracy in gas-phase thermochemical properties. Their biggest computational bottleneck is the evaluation of the valence post-CCSD(T) correction term. We demonstrate here, for the W4-17 thermochemistry benchmark and subsets thereof, that the lambda coupled cluster expansion converges more rapidly and smoothly than the regular coupled cluster series. By means of CCSDT(Q) $_{I^} $ and CCSDTQ(5) $_{I^} $ , we can considerably (up to an order of magnitude) accelerate W4- and W4.3-type calculations without loss in accuracy, leading to the W4 $I^$ and W4.3 $I^$ computational thermochemistry protocols.

J. Phys. Chem. A 128, 1715-1724 (2024). PDF is CC:BY 4.0

W4I^: leveraging I^ coupled cluster for accurate computational thermochemistry approaches

Abstract

W4 $I^$ : leveraging $I^$ coupled cluster for accurate computational thermochemistry approaches