Known Issues
As with all software, also DIRAC has bugs that are either hard to find and fix or occur in external software (compilers, libraries) that are not under our control. On this page we keep a list of important known issues and (if possible) work-arounds. A more extensive list is found at the issues page of our gitlab repository.
February 25, 2026: Issues affecting DIRAC26 and likely also earlier versions.
1. On many systems, part of the functionality (mcscf, exacorr coupled cluster) is not working correctly for parallel runs.
Work-around is all cases possible by running single node runs.
The exacorr issues are caused by non-maintenance of the ExaTensor external library. We are in the process of switching to another library for parallel tensor contraction. For parallel coupled cluster calculations, users can employ the older relccsd implementation that does not use the ExaTensor library and has most of the functionality as well.
Other issues with parallel calculations concern quite specific use cases that are tracked on our gitlab issue list and will be fixed on a case-by-case basis.
2. The exacorr coupled cluster functionality is affected by a GNU compiler bug for version 14.2 and higher on Mx (x = 1, 2, 3) Apple systems.
In particular the computed triples energies can not be trusted, check whether tests pass before employing this system for production.
Work-around is to employ a compiler version older than 14.2