BAGEL
A parallel electronic-structure library with multiconfigurational wavefunctions, perturbation theory, nuclear gradients and relativistic methods.
Where it fits
Multireference excited-state studies and research workflows requiring analytic gradients.
Limits and practical considerations
Compilation dependencies and method-specific derivative support need checking before adoption.
Licensing and access
Distributed under the GNU GPL; inspect the selected source release and dependency licences.
Official documentation and project