DIRAC
Relativistic atomic and molecular electronic-structure software for treating heavy-element effects and molecular properties with two- and four-component methods.
Where it fits
Heavy-element chemistry, spin–orbit effects and relativistic property benchmarks.
Limits and practical considerations
Relativistic Hamiltonian, basis balance and correlation choices require specialist validation.
Licensing and access
Open source under LGPL-2.1-only since DIRAC22; consult bundled component terms.
Official documentation and project