Issue 32, 2023

Sub 20 cm−1 computational prediction of the CH bond energy – a case of systematic error in computational thermochemistry

Abstract

The bond dissociation energy of methylidyne, D0(CH), is studied using an improved version of the High-Accuracy Extrapolated ab initio Thermochemistry (HEAT) approach as well as the Feller–Peterson–Dixon (FPD) model chemistry. These calculations, which include basis sets up to nonuple (aug-cc-pCV9Z) quality, are expected to be capable of providing results substantially more accurate than the ca. 1 kJ mol−1 level that is characteristic of standard high-accuracy protocols for computational thermochemistry. The calculated 0 K CH bond energy (27 954 ± 15 cm−1 for HEAT and 27 956 ± 15 cm−1 for FPD), along with equivalent treatments of the CH ionization energy and the CH+ dissociation energy (85 829 ± 15 cm−1 and 32 946 ± 15 cm−1, respectively), were compared to the existing benchmarks from Active Thermochemical Tables (ATcT), uncovering an unexpected difference for D0(CH). This has prompted a detailed reexamination of the provenance of the corresponding ATcT benchmark, allowing the discovery and subsequent correction of a systematic error present in several published high-level calculations, ultimately yielding an amended ATcT benchmark for D0(CH). Finally, the current theoretical results were added to the ATcT Thermochemical Network, producing refined ATcT estimates of 27 957.3 ± 6.0 cm−1 for D0(CH), 32 946.7 ± 0.6 cm−1 for D0(CH+), and 85 831.0 ± 6.0 cm−1 for IE(CH).

Graphical abstract: Sub 20 cm−1 computational prediction of the CH bond energy – a case of systematic error in computational thermochemistry

Supplementary files

Article information

Article type
Paper
Submitted
26 aug 2022
Accepted
27 sep 2022
First published
03 okt 2022

Phys. Chem. Chem. Phys., 2023,25, 21162-21172

Author version available

Sub 20 cm−1 computational prediction of the CH bond energy – a case of systematic error in computational thermochemistry

J. H. Thorpe, D. Feller, D. H. Bross, B. Ruscic and J. F. Stanton, Phys. Chem. Chem. Phys., 2023, 25, 21162 DOI: 10.1039/D2CP03964H

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