OpenBabel Backend

OpenBabel is available in PyAR as a lightweight molecular preparation and optimisation route through commands such as obabel, babel, obminimize, and obenergy.

When to use OpenBabel

Use obabel when:

  • you need a lightweight structure preparation or force-field-style route

  • you want a quick geometry cleanup before more serious calculations

  • charge and multiplicity handling are not central to the calculation

Example command

pyar-optimiser structure.xyz --software obabel

Practical notes

  • OpenBabel tools must be installed separately and available on PATH.

  • This route is best treated as lightweight preparation, not final chemistry.

  • For reaction or mechanistic work, prefer xTB, AIMNet2, ORCA, Gaussian, or a validated higher-level backend.

AFIR/geomeTRIC status

obabel is not currently registered as an energy-gradient provider for the geomeTRIC-backed AFIR reaction route.