Active Thermochemical Tables (ATcT) have been hailed in the scientific literature as the most significant improvement in thermodynamics in decades. The availability of reliable, high-quality thermochemical values is critical in many areas of chemistry, and is a <i>conditio sine qua non</i> in the development of predictive models of complex chemical environments, ranging from combustion and atmospheric chemistry to astrochemistry, as well as in the development and improvement of state-of-the-art electronic structure computational treatments that are now capable of sub-kJ/mol accuracies. ATcT are a distinctly different paradigm that enables the derivation of accurate and reliable thermodynamic properties for a broad range of chemical species, based on constructing, analyzing, and solving a Thermochemical Network (TN), thus circumventing inherent problems of the tralatitious sequential approach to thermochemistry. The TN contains available thermochemical interdependencies between the targeted chemical species, such as reaction enthalpies or free energies, constants of equilibria, adiabatic ionization energies and electron affinities, etc., irrespective of whether these were determined via experiment or highly accurate theory. The TN effectively represents a set of qualified constraints that must be simultaneously satisfied by the resulting enthalpies of formation. ATcT construct and statistically analyze the TN, trying to identify constraints that may be - because of finite measurement accuracies - inconsistent with the prevailing knowledge content of the TN. The end result is the extraction of the best possible thermochemistry, based on optimally using all of the currently available knowledge. Moreover, ATcT offer a number of additional features that are not available (nor possible) in the traditional approach. With ATcT, new knowledge can be painlessly added and propagated through all affected thermochemical values. ATcT also allow hypothesis testing and evaluation, as well as discovery of weak links in the TN, which provide pointers to new determinations that can efficiently improve the underlying body of knowledge. New ATcT results are posted periodically on the ATcT website, atct.anl.gov, which typically receives 25,000-35,000 unique visitors each month.

Active thermochemical tables: At the junction of theory and experiment

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.