Input File Format¶

OpenQP inputs are INI-like text files. Options are grouped by section:

[input]
runtype=energy
method=hf
basis=6-31g*

[scf]
type=rhf

Lines beginning with # are comments. Keyword names are case-insensitive in normal use, but this manual uses lower-case names to match the Python schema.

Geometry¶

Inline coordinates are written under [input] system with indented atom lines:

[input]
system=
   O   0.000000000   0.000000000  -0.041061554
   H  -0.533194329   0.533194329  -0.614469223
   H   0.533194329  -0.533194329  -0.614469223

An external XYZ file can be used instead:

[input]
system=h2o.xyz

Some workflows, such as NACME, also use [input] system2 for the displaced or previous geometry.

Core Sections¶

Section	Purpose
`[input]`	Charge, basis, method, run type, geometry, AO convention, threading.
`[guess]`	Initial orbitals and restart data.
`[scf]`	RHF/ROHF/UHF reference and SCF convergence controls.
`[dftgrid]`	DFT functional/grid controls.
`[tdhf]`	TDHF, TDDFT, SF-TDDFT, MRSF-TDDFT, and UMRSF settings.
`[properties]`	Gradients, NAC, NMR, export, and property requests.
`[optimize]`	Geometry-optimization target and convergence controls.
`[oqp]`	Native optimizer controls.
`[geometric]`	geomeTRIC backend controls.
`[pcm]`	Reference-SCF PCM/ddX energy settings.
`[symmetry]`	Point-group metadata and optional symmetry reductions.
`[hess]`	Hessian and frequency controls.
`[nac]`	NAC/NACME controls.
`[ekt]`	MRSF-EKT IP/EA channel selection.
`[neb]`	NEB product and image controls.

Run Types¶

Common [input] runtype values:

Run type	Meaning
`energy`	Single-point energy and requested properties.
`grad`	Energy plus gradient for the requested state.
`hess`	Hessian/frequency workflow.
`nacme`	Time/geometric derivative coupling between MRSF states.
`soc`	MRSF-TDDFT spin-orbit coupling workflow.
`ekt`	MRSF-EKT ionization-potential/electron-affinity workflow.
`optimize`	Geometry optimization.
`meci`, `mecp`, `tci`	Crossing-point searches.
`ts`, `irc`, `neb`, `mep`	Reaction-path workflows.
`prop`, `data`	Multi-state property/gradient workflows for downstream drivers.

md is recognized by validation code but is not the current production workflow in this repository.