SIESTA
An electronic-structure and atomistic-simulation package using localized numerical atomic orbitals and pseudopotentials for molecules and extended materials.
Where it fits
Localized-basis studies of larger structures and associated transport workflows.
Limits and practical considerations
Basis range and completeness require careful testing; transport modules add their own setup requirements.
Licensing and access
Current SIESTA is GPL-3.0-only; older academic-only licensing descriptions do not describe current releases.