pKa

pKa workflow - predict acid/base dissociation constants.

pKaMicrostate dataclass

pKaMicrostate(atom_index: int, pka: float, smiles: str | None = None, delta_g: float | None = None, uncertainty: float | None = None)

Microstate from a pKa calculation.

Available fields depend on the pKa method used. 3D structure-based methods (aimnet2_wagen2024, gxtb_wagen2026) populate delta_g. SMILES-based methods (chemprop_nevolianis2025, starling) populate smiles; chemprop_nevolianis2025 also populates uncertainty.

Attributes:

Name	Type	Description
atom_index	int	index of the protonation site atom
pka	float	predicted pKa value
smiles	str | None	SMILES of the microstate (SMILES-based methods only)
delta_g	float | None	free energy of (de)protonation in kcal/mol (3D structure-based methods only)
uncertainty	float | None	prediction uncertainty (chemprop_nevolianis2025 only)

pKaResult dataclass

pKaResult(workflow_data: dict[str, Any], workflow_type: str, workflow_uuid: str, complete: bool = True)

Bases: WorkflowResult

Result from a pKa workflow.

strongest_acid property

strongest_acid: float | None

Strongest acidic site pKa value.

strongest_base property

strongest_base: float | None

Strongest basic site pKa value.

conjugate_acids property

conjugate_acids: list[pKaMicrostate]

List of conjugate acid microstates with pKa values.

conjugate_bases property

conjugate_bases: list[pKaMicrostate]

List of conjugate base microstates with pKa values.

structures property

structures: list[Calculation]

Optimized structure calculations (lazily fetched).

Only available for 3D structure-based methods (aimnet2_wagen2024, gxtb_wagen2026).

Note

Makes one API call per structure on first access. Results are cached. Call clear_cache() to refresh.

Raises:

Type	Description
ValueError	method is SMILES-based (chemprop_nevolianis2025, starling)

submit_pka_workflow

submit_pka_workflow(initial_molecule: StructureInput | SMILES, pka_range: tuple[int, int] = (2, 12), method: Literal['aimnet2_wagen2024', 'gxtb_wagen2026', 'chemprop_nevolianis2025', 'starling'] = 'gxtb_wagen2026', solvent: SolventInput = 'water', deprotonate_elements: list[int] | None = None, protonate_elements: list[int] | None = None, mode: Mode = Mode.CAREFUL, name: str = 'pKa Workflow', folder_uuid: str | None = None, folder: Folder | None = None, max_credits: int | None = None, webhook_url: str | None = None, is_draft: bool = False) -> Workflow[pKaResult]

Submits a pKa workflow to the API.

Parameters:

Name	Type	Description	Default
initial_molecule	StructureInput | SMILES	molecule to calculate pKa for. Accepts Molecule, stjames.Molecule, RDKit Mol, dict, or SMILES string	required
pka_range	tuple[int, int]	range of pKa values to calculate	(2, 12)
method	Literal['aimnet2_wagen2024', 'gxtb_wagen2026', 'chemprop_nevolianis2025', 'starling']	algorithm used to compute pKa values: - aimnet2_wagen2024: AIMNet2-based; requires 3D structure; water only. - gxtb_wagen2026: g-xTB-based; requires 3D structure; water only; full periodic table. - chemprop_nevolianis2025: Chemprop-based; requires SMILES; several solvents supported. - starling: SMILES-based; water only	'gxtb_wagen2026'
solvent	SolventInput	solvent in which pKa values will be computed	'water'
deprotonate_elements	list[int] | None	elements to deprotonate (atomic numbers)	None
protonate_elements	list[int] | None	elements to protonate (atomic numbers)	None
mode	Mode	mode to run the calculation in	CAREFUL
name	str	name of the workflow	'pKa Workflow'
folder_uuid	str | None	UUID of the folder to place the workflow in	None
folder	Folder | None	destination folder	None
max_credits	int | None	maximum credits for the workflow	None
webhook_url	str | None	URL that Rowan will POST to when the workflow completes	None
is_draft	bool	save as a draft without starting execution	False

Returns:

Type	Description
Workflow[pKaResult]	submitted workflow

Raises:

Type	Description
ValueError	method/input type mismatch, or chemprop used with protonate_elements
HTTPStatusError	request to the API fails