COLUMBUS
A multireference electronic-structure suite offering MCSCF, MR-CISD, MR-ACPF and MR-AQCC, with gradients and selected nonadiabatic couplings.
Where it fits
Bond breaking, electronic excited states and conical-intersection studies.
Limits and practical considerations
Reference configurations and active spaces need physical justification; large CI expansions can be costly.
Licensing and access
Open source under LGPL; official source and binary releases are provided through GitLab.
Official documentation and project