ORCA is an ab initio quantum chemistry program package that contains modern electronic structure methods including density functional theory, many-body perturbation, coupled cluster, multireference methods, and semi-empirical quantum chemistry methods. Its main field of application is larger molecules, transition metal complexes, and their spectroscopic properties.
ORCA 5.0 is not just an update to the program. Even if much of the output will look very similar to previous versions, ORCA 5.0 is pretty much a completely new program. We have spent major efforts in redesigning and streamlining the core engine of the program. In fact, in designing the new engine, we have deeply re-thought the conceptual basis for quantum chemical program development for the next decades to come. The result is a program that is much leaner, much more efficient and much fitter for future extensions in an ever shifting hardware landscape. The full transition to our final vision of a modern quantum chemical program suite will likely be completed with ORCA 6, that we plan to release 2022. However, the improvements made in ORCA 5.0 are so numerous and so vast that we felt that now is the appropriate moment to share our work with the general public.
The link to the download is on the ORCA forum (requires registration) https://orcaforum.kofo.mpg.de/app.php/dlext/?cat=13.