Elaborated thermochemical treatment of HF, CO, N2, and H2O: Insight into HEAT and its extensions

James H Thorpe; Josie L Kilburn; David Feller; P Bryan Changala; David H Bross; Branko Ruscic; John F Stanton

doi:10.1063/5.0069322

Elaborated thermochemical treatment of HF, CO, N₂, and H₂O: Insight into HEAT and its extensions

J Chem Phys. 2021 Nov 14;155(18):184109. doi: 10.1063/5.0069322.

Authors

James H Thorpe¹, Josie L Kilburn¹, David Feller², P Bryan Changala³, David H Bross⁴, Branko Ruscic⁴, John F Stanton¹

Affiliations

¹ The Quantum Theory Project, Department of Chemistry, The University of Florida, Gainesville, Florida 32611, USA.
² Washington State University, Pullman, Washington 99164-4630, USA and University of Alabama, Tuscaloosa, Alabama 35487-0336, USA.
³ Center for Astrophysics, Harvard|Smithsonian, Cambridge, Massachusetts 02138, USA.
⁴ Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.

PMID: 34773951
DOI: 10.1063/5.0069322

Abstract

Empirical, highly accurate non-relativistic electronic total atomization energies (eTAEs) are established by combining experimental or computationally converged treatments of the nuclear motion and relativistic contributions with the total atomization energies of HF, CO, N₂, and H₂O obtained from the Active Thermochemical Tables. These eTAEs, which have estimated (2σ) uncertainties of less than 10 cm^-1 (0.12 kJ mol^-1), form the basis for an analysis of high-level ab initio quantum chemical calculations that aim at reproducing these eTAEs for the title molecules. The results are then employed to analyze the performance of the high-accuracy extrapolated ab initio thermochemistry, or High-Accuracy Extrapolated Ab Initio Thermochemistry (HEAT), family of theoretical methods. The method known as HEAT-345(Q), in particular, is found to benefit from fortuitous error cancellation between its treatment of the zero-point energy, extrapolation errors in the Hartree-Fock and coupled cluster contributions, neglect of post-(T) core-correlation, and the basis-set error involved in higher-level correlation corrections. In addition to shedding light on a longstanding curiosity of the HEAT protocol-where the cheapest HEAT-345(Q) performs comparably to the theoretically more complete HEAT-456QP procedure-this study lays the foundation for extended HEAT variants that offer substantial improvements in accuracy relative to the established approaches.