About two years ago I integrated my open-source ctx library into the Q-Chem quantum-chemistry software suite. Quickly ctx became part of the core stack for managing computational results inside Q-Chem. In particular inside the ccman and adcman modules, which are responsible for most of the coupled-cluster and algebraic-diagrammatic construction methods available in Q-Chem, ctx is widely used.

In a recently published paper by all the Q-Chem authors the developments inside the Q-Chem package leading up the major version 5 of the software are now summarised. The full abstract reads

This article summarizes technical advances contained in the fifth major release of the Q-Chem quantum chemistry program package, covering developments since 2015. A comprehensive library of exchange-correlation functionals, along with a suite of correlated many-body methods, continues to be a hallmark of the Q-Chem software. The many-body methods include novel variants of both coupled-cluster and configuration-interaction approaches along with methods based on the algebraic diagrammatic construction and variational reduced density-matrix methods. Methods highlighted in Q-Chem 5 include a suite of tools for modeling core-level spectroscopy, methods for describing metastable resonances, methods for computing vibronic spectra, the nuclear–electronic orbital method, and several different energy decomposition analysis techniques. High-performance capabilities including multithreaded parallelism and support for calculations on graphics processing units are described. Q-Chem boasts a community of well over 100 active academic developers, and the continuing evolution of the software is supported by an "open teamware" model and an increasingly modular design.

Article
Evgeny Epifanovsky, Andrew T. B. Gilbert, Xintian Feng and others. Software for the frontiers of quantum chemistry: An overview of developments in the Q-Chem 5 package. Journal of Chemical Physics, 155, 084801 (2021). DOI 10.1063/5.0055522