Keyword Reference¶

This chapter is the book-style reference for OpenQP's section-level settings. Workflow pages lead with the recommended .oqp form, then Python, and finally a legacy sectioned .inp equivalent. This chapter explains the underlying section keywords, their value types and defaults, and the workflow constraints enforced by the input checker.

The entries are aligned with these OpenQP source files:

How to Read an Entry¶

Each keyword entry uses the same structure:

Field	Meaning
Type	The parsed value type used by OpenQP.
Default	The value inserted when the keyword is omitted.
Values	Allowed or commonly used values. If validation enforces a finite set, that set is listed.
Used by	The workflows or code paths that normally read the keyword.
Description	The practical meaning of the keyword.
Notes	Interactions with other keywords, limitations, and common mistakes.

Boolean keywords accept ordinary true/false spellings such as true, false, yes, no, 1, and 0 unless a keyword documents a narrower set.

Numeric state indices in traditional sectioned input are workflow dependent. HF/DFT reference-state properties use state 0. Ordinary TDHF/TDDFT state 1 means the first excited state. SF-TDDFT and MRSF-TDDFT internal state 1 means the lowest response target. The .oqp format hides that offset: MRSF uses physical S0, T0, and Q0, while SF uses root=1. See .oqp input.

Method background and literature pointers are collected in References. The keyword pages link there for MRSF-TDDFT, MP2, SOC, scalar relativistic correction, and PCM/ddX rather than repeating full bibliographies inside each keyword entry.

Section Index¶

Section	Purpose
`[input]`	Global calculation setup, geometry, run type, AO convention, threading.
`[d4]`	Complete explicit DFT-D4 rational-damping parameter set.
`[guess]`	Initial orbitals, restart files, and MO swaps.
`[scf]`	Reference type, convergence controls, pFON, TRAH, fallback manager.
`[mp2]`	Standalone MP2 spin-scaling controls.
`[dftb]`	DFTB backend, SCC, response, spin, and MRSF-TDDFTB controls.
`[dftgrid]`	DFT quadrature and hybrid/range-separated functional controls.
`[tdhf]`	TDHF/TDDFT/SF/MRSF/UMRSF response settings.
`[md]`	Nonadiabatic surface-hopping molecular dynamics (`runtype=namd`), including SOC-NAMD.
`[qmmm]`	Hybrid QM/MM setup: QM region, force field, ESPF embedding, and link atoms.
`[properties]`	Gradients, NMR, export, and property requests.
`[hess]`	Hessian, frequency, and thermochemistry controls.
`[nac]`	NAC and NACME state-pair controls.
`[ekt]`	MRSF-EKT IP/EA channel selection.
`[optimize]`	Target state and optimization convergence controls.
`[oqp]`	Native optimizer controls.
`[geometric]`	Optional legacy geomeTRIC controls for traditional `.inp` and Python workflows.
`[neb]`	NEB endpoints plus traditional `.inp` geomeTRIC compatibility controls.
`[pcm]`	Reference-SCF PCM/ddX settings.
`[symmetry]`	Point-group metadata and optional symmetry reductions.
`[json]`	Advanced JSON/restart metadata used by internal interfaces.
`[tests]`	Regression-test expectation controls.

Documentation Rule¶

When an OpenQP pull request changes a default, accepted value, validation rule, or workflow scope, update the matching keyword page in this documentation repository before the next release.