Input Validation #

Overview #

pychum validates input at dataclass construction time using __post_init__ methods. Validation is inline – the _validators.py file exists as an empty placeholder for future extraction.

All validation happens when a dataclass is instantiated. Invalid values raise ValueError immediately, before any rendering occurs. This catches configuration errors at load time rather than producing malformed input files.

Validated Fields #

Atom #

Condition	Error
`point_charge` is `None` and `symbol` is `None`	“Atom symbol is required unless it’s a point charge.”

When point_charge is set, symbol is forced to "Q" (no error).

OptimSettings #

Field	Allowed values
`method`	LBFGS, VPO, FIRE

Comparison is case-insensitive (.upper()).

ReparamSettings #

Field	Allowed values
`interp`	linear, cubic

Comparison is case-insensitive (.lower()).

FreeEndSettings #

Field	Allowed values
`opt_type`	PERP, CONTOUR, FULL

Comparison is case-insensitive (.upper()).

ZoomSettings #

Field	Allowed values
`interpolation`	linear, cubic

Comparison is case-insensitive (.lower()).

SpringSettings #

Field	Allowed values
`spring_kind`	image, dof, ideal
`perpspring`	no, cos, tan, cosTan, DNEB

Both comparisons are case-insensitive (.lower()).

NebBlock #

Field	Allowed values
`convtype`	all, cionly
`quatern`	no, startonly, always
`tangent`	improved, original
`interpolation`	IDPP, LINEAR, XTB1TS, XTB1, XTB2TS, XTB2

convtype, quatern, and tangent use .lower(). interpolation uses .upper().

RestartSettings #

Condition	Error
Both `gbw_basename` and `allxyz` are set	“Only one of gbw_basenameor allxyz should be provided.”

TSGuessSettings #

Condition	Error
Both `xyz_struct` and `pdb_struct` are set	“Only one of xyz_structor pdb_structshould be provided.”

Unvalidated Fields #

Most numeric fields (tolerances, step sizes, spring constants) accept any value without range checking. Boolean fields are not validated. The ConfigLoader relies on TOML parsing to enforce basic type correctness.

Template-level Validation #

The geom_scan.jinja template has an additional guard: if the total number of scan coordinates (bonds + angles + dihedrals) exceeds 3, it emits an error message instead of rendering the scan block. This is a template-level check, not a dataclass validator.

Future Work #

The empty _validators.py and _orcablocks.py placeholders suggest planned extraction of validation logic into dedicated modules. Currently all validation is co-located with the dataclass definitions.