Psi4 RT-TDDFT driver (rttddft)

Confirm prerequisites

• Ensure psi4 is installed and importable in the driver environment.
• Provide an XYZ geometry file whose second line specifies charge and multiplicity (e.g., 0 1).

Configure socket mode

• Run:

- mxldriver --model rttddft --address <host> --port <port> --param "moleculexyz=../tddftbenchmark/hcn.xyz, functional=b3lyp, basis=cc-pvdz, dtrttddftau=0.04, dftgridname=SG1, electronpropagation=pc, thresholdpc=1e-6, memory=16GB, numthreads=16" --verbose

Configure embedded mode

• Instantiate:

- Molecule(driver="rttddft", driver_kwargs={...})

Notes

• Keep dtrttddftau small enough for stable electronic propagation; the driver can sub-step under a larger EM time step.
• On HPC, match numthreads to --cpus-per-task (single driver) or set numthreads=1 when launching many drivers in the same SLURM job.
• Use checkpoint=true and restart=true for long jobs or unstable HPC environments.
• Read full parameter docs in docs/source/drivers/rttddft.rst.