Psi4 Backend

Psi4 is listed as a quantum-chemistry backend family in PyAR. It can be useful for users who have a local Psi4 installation and want to connect PyAR-generated structures to Psi4 calculations.

When to use Psi4

Use psi4 when:

  • Psi4 is installed and configured on your system

  • you specifically want to test a Psi4-based route

  • you are comfortable validating backend behaviour on small examples before larger PyAR runs

Example command

pyar-optimiser structure.xyz -c 0 -m 1 --software psi4

Practical notes

  • Psi4 must be installed separately.

  • The current capability registry does not mark psi4 as a registered energy-gradient provider for the geomeTRIC AFIR route.

  • Use a small validation case before relying on Psi4 outputs in a larger PyAR workflow.

AFIR/geomeTRIC status

psi4 is not currently registered as an energy-gradient provider for the geomeTRIC-backed AFIR reaction route.