Revisiting the thermochemistry of chlorine fluorides

TL;DR

This paper reevaluates the thermochemistry of chlorine fluorides using advanced quantum calculations, highlighting limitations of standard methods and exploring alternative computational approaches for accurate thermodynamic data.

Contribution

It demonstrates that CCSD(T) may not always provide chemical accuracy for chlorine fluorides and compares its performance with DFT methods.

Findings

CCSD(T) struggles with accurate enthalpy predictions for chlorine fluorides.

Density functional theory offers a computationally cheaper alternative with reasonable accuracy.

Thermodynamic quantities were calculated across various temperatures.

Abstract

In this work, accurate calculations of standard enthalpies of formation of chlorine fluorides (ClF$_n$, n=1--7; Cl$_2$F and Cl$_3$F$_2$) were performed through the isodesmic reactions scheme. It is argued that, for many chlorine fluorides, the gold standard method of quantum chemistry (CCSD(T)) is not capable to predict enthalpy values nearing chemical accuracy if atomization scheme is used. This is underpinned by a thorough analysis of total atomization energy results and the inspection of multireference features of these compounds. Other thermodynamic quantities were also calculated at different temperatures. In order to complement the energetic description, elimination curves were studied through density functional theory as a computationally affordable alternative to highly correlated wave function-based methods.