## Stop

**post** `/compute/v1/small-molecule/library-screen/{id}/stop`

Stop an in-progress library screen early

### Path Parameters

- `id: string`

### Returns

- `id: string`

  Unique SmScreen identifier

- `completed_at: string`

- `created_at: string`

- `data_deleted_at: string`

  When the input, output, and result data was permanently deleted. Null if data has not been deleted.

- `engine: "boltz-sm-screen"`

  Engine used for small molecule library screen

  - `"boltz-sm-screen"`

- `engine_version: string`

  Engine version used for small molecule library screen

- `error: object { code, message, details }`

  - `code: string`

    Machine-readable error code

  - `message: string`

    Human-readable error message

  - `details: optional unknown`

    Additional field-level error details keyed by input path, when available.

- `input: object { molecules, target, molecule_filters }`

  Pipeline input (null if data deleted)

  - `molecules: object { url, url_expires_at }`

    - `url: string`

      URL to download the file

    - `url_expires_at: string`

      When the presigned URL expires

  - `target: object { entities, bonds, constraints, 2 more }`

    Target protein with binding pocket for small molecule design or screening

    - `entities: array of object { chain_ids, type, value, 2 more }`

      Protein entities defining the target structure. Each entity represents a protein chain.

      - `chain_ids: array of string`

        Chain IDs for this entity

      - `type: "protein"`

        - `"protein"`

      - `value: string`

        Amino acid sequence (one-letter codes)

      - `cyclic: optional boolean`

        Whether the sequence is cyclic

      - `modifications: optional array of object { residue_index, type, value }  or object { residue_index, type, value }`

        Post-translational modifications. Optional; defaults to an empty list when omitted.

        - `CcdModificationResponse = object { residue_index, type, value }`

          - `residue_index: number`

            0-based index of the residue to modify

          - `type: "ccd"`

            - `"ccd"`

          - `value: string`

            CCD code from RCSB PDB (e.g. 'MSE' for selenomethionine, 'SEP' for phosphoserine)

        - `SmilesModificationResponse = object { residue_index, type, value }`

          - `residue_index: number`

            0-based index of the residue to modify

          - `type: "smiles"`

            - `"smiles"`

          - `value: string`

            SMILES string for the modification

    - `bonds: optional array of object { atom1, atom2 }`

      Covalent bond constraints between atoms in the target complex. Atom-level ligand references currently support ligand_ccd only; ligand_smiles is unsupported.

      - `atom1: object { atom_name, chain_id, type }  or object { atom_name, chain_id, residue_index, type }`

        Ligand atom reference. Atom-level ligand references currently support ligand_ccd entities only; ligand_smiles is unsupported.

        - `LigandAtomResponse = object { atom_name, chain_id, type }`

          Ligand atom reference. Atom-level ligand references currently support ligand_ccd entities only; ligand_smiles is unsupported.

          - `atom_name: string`

            Standardized atom name (verifiable in CIF file on RCSB). Atom-level references to ligand_smiles entities are currently unsupported; use ligand_ccd instead.

          - `chain_id: string`

            Chain ID containing the atom

          - `type: "ligand_atom"`

            - `"ligand_atom"`

        - `PolymerAtomResponse = object { atom_name, chain_id, residue_index, type }`

          - `atom_name: string`

            Standardized atom name (verifiable in CIF file on RCSB)

          - `chain_id: string`

            Chain ID containing the atom

          - `residue_index: number`

            0-based residue index

          - `type: "polymer_atom"`

            - `"polymer_atom"`

      - `atom2: object { atom_name, chain_id, type }  or object { atom_name, chain_id, residue_index, type }`

        Ligand atom reference. Atom-level ligand references currently support ligand_ccd entities only; ligand_smiles is unsupported.

        - `LigandAtomResponse = object { atom_name, chain_id, type }`

          Ligand atom reference. Atom-level ligand references currently support ligand_ccd entities only; ligand_smiles is unsupported.

          - `atom_name: string`

            Standardized atom name (verifiable in CIF file on RCSB). Atom-level references to ligand_smiles entities are currently unsupported; use ligand_ccd instead.

          - `chain_id: string`

            Chain ID containing the atom

          - `type: "ligand_atom"`

            - `"ligand_atom"`

        - `PolymerAtomResponse = object { atom_name, chain_id, residue_index, type }`

          - `atom_name: string`

            Standardized atom name (verifiable in CIF file on RCSB)

          - `chain_id: string`

            Chain ID containing the atom

          - `residue_index: number`

            0-based residue index

          - `type: "polymer_atom"`

            - `"polymer_atom"`

    - `constraints: optional array of object { binder_chain_id, contact_residues, max_distance_angstrom, 2 more }  or object { max_distance_angstrom, token1, token2, 2 more }`

      Structural constraints (pocket and contact). Atom-level ligand references currently support ligand_ccd only; ligand_smiles is unsupported.

      - `PocketConstraintResponse = object { binder_chain_id, contact_residues, max_distance_angstrom, 2 more }`

        Constrains the binder to interact with specific pocket residues on the target.

        - `binder_chain_id: string`

          Chain ID of the binder molecule

        - `contact_residues: map[array of number]`

          Binding pocket residues keyed by chain ID. Each key is a chain ID (e.g. "A") and the value is an array of 0-indexed residue indices that define the pocket on that chain.

        - `max_distance_angstrom: number`

          Maximum allowed distance in Angstroms between binder and pocket residues. Typical range: 4-8 A.

        - `type: "pocket"`

          - `"pocket"`

        - `force: optional boolean`

          Whether to force the constraint

      - `ContactConstraintResponse = object { max_distance_angstrom, token1, token2, 2 more }`

        Contact constraint between two tokens. Atom-level ligand references currently support ligand_ccd entities only; ligand_smiles is unsupported.

        - `max_distance_angstrom: number`

          Maximum distance in Angstroms

        - `token1: object { chain_id, residue_index, type }  or object { atom_name, chain_id, type }`

          Ligand contact token. Atom-level ligand references currently support ligand_ccd entities only; ligand_smiles is unsupported.

          - `PolymerContactTokenResponse = object { chain_id, residue_index, type }`

            - `chain_id: string`

              Chain ID

            - `residue_index: number`

              0-based residue index

            - `type: "polymer_contact"`

              - `"polymer_contact"`

          - `LigandContactTokenResponse = object { atom_name, chain_id, type }`

            Ligand contact token. Atom-level ligand references currently support ligand_ccd entities only; ligand_smiles is unsupported.

            - `atom_name: string`

              Atom name. Atom-level references to ligand_smiles entities are currently unsupported; use ligand_ccd instead.

            - `chain_id: string`

              Chain ID

            - `type: "ligand_contact"`

              - `"ligand_contact"`

        - `token2: object { chain_id, residue_index, type }  or object { atom_name, chain_id, type }`

          Ligand contact token. Atom-level ligand references currently support ligand_ccd entities only; ligand_smiles is unsupported.

          - `PolymerContactTokenResponse = object { chain_id, residue_index, type }`

            - `chain_id: string`

              Chain ID

            - `residue_index: number`

              0-based residue index

            - `type: "polymer_contact"`

              - `"polymer_contact"`

          - `LigandContactTokenResponse = object { atom_name, chain_id, type }`

            Ligand contact token. Atom-level ligand references currently support ligand_ccd entities only; ligand_smiles is unsupported.

            - `atom_name: string`

              Atom name. Atom-level references to ligand_smiles entities are currently unsupported; use ligand_ccd instead.

            - `chain_id: string`

              Chain ID

            - `type: "ligand_contact"`

              - `"ligand_contact"`

        - `type: "contact"`

          - `"contact"`

        - `force: optional boolean`

          Whether to force the constraint

    - `pocket_residues: optional map[array of number]`

      Binding pocket residues, keyed by chain ID. Each key is a chain ID (e.g. "A") and the value is an array of 0-indexed residue indices that define the binding pocket on that chain. When provided, these residues guide pocket extraction and add a derived pocket constraint during affinity predictions. That derived constraint remains separate from any explicit pocket constraints in target.constraints. When omitted, the model auto-detects the pocket.

    - `reference_ligands: optional array of string`

      Reference ligands as SMILES strings that help the model identify the binding pocket. When omitted, a set of drug-like default ligands is used for pocket detection.

  - `molecule_filters: optional object { boltz_smarts_catalog_filter_level, custom_filters }`

    Molecule filtering configuration. Controls both Boltz built-in SMARTS filtering and custom filters.

    - `boltz_smarts_catalog_filter_level: optional "recommended" or "extra" or "aggressive" or "disabled"`

      Controls the stringency of Boltz's built-in SMARTS structural alert filtering, which removes molecules matching known problematic substructures. 'recommended' (default): applies a curated set of alerts balancing safety and hit rate. 'extra': adds additional alerts beyond the recommended set for stricter filtering. 'aggressive': applies the most comprehensive alert set — may reject viable molecules. 'disabled': turns off Boltz SMARTS filtering entirely; only custom_filters will be applied.

      - `"recommended"`

      - `"extra"`

      - `"aggressive"`

      - `"disabled"`

    - `custom_filters: optional array of object { max_hba, max_hbd, max_logp, 3 more }  or object { type, fraction_csp3, mol_logp, 8 more }  or object { patterns, type }  or 2 more`

      Custom filters to apply. Molecules must pass all filters (AND logic).

      - `LipinskiFilterResponse = object { max_hba, max_hbd, max_logp, 3 more }`

        Lipinski's Rule of Five filter. Rejects molecules that violate drug-likeness criteria based on molecular weight, LogP, hydrogen bond donors, and hydrogen bond acceptors.

        - `max_hba: number`

          Maximum number of hydrogen bond acceptors. Lipinski threshold: 10

        - `max_hbd: number`

          Maximum number of hydrogen bond donors. Lipinski threshold: 5

        - `max_logp: number`

          Maximum LogP. Lipinski threshold: 5

        - `max_mw: number`

          Maximum molecular weight (Da). Lipinski threshold: 500

        - `type: "lipinski_filter"`

          - `"lipinski_filter"`

        - `allow_single_violation: optional boolean`

          If true, one rule violation is allowed (classic Rule of Five). Defaults to false (all rules must pass).

      - `RdkitDescriptorFilterResponse = object { type, fraction_csp3, mol_logp, 8 more }`

        Filter molecules by RDKit molecular descriptors. Each descriptor is constrained to a min/max range. Only descriptors you provide are checked — omitted descriptors are unconstrained.

        - `type: "rdkit_descriptor_filter"`

          - `"rdkit_descriptor_filter"`

        - `fraction_csp3: optional object { max, min }`

          Min/max range constraint for an RDKit molecular descriptor

          - `max: optional number`

            Maximum allowed value (inclusive)

          - `min: optional number`

            Minimum allowed value (inclusive)

        - `mol_logp: optional object { max, min }`

          Min/max range constraint for an RDKit molecular descriptor

          - `max: optional number`

            Maximum allowed value (inclusive)

          - `min: optional number`

            Minimum allowed value (inclusive)

        - `mol_wt: optional object { max, min }`

          Min/max range constraint for an RDKit molecular descriptor

          - `max: optional number`

            Maximum allowed value (inclusive)

          - `min: optional number`

            Minimum allowed value (inclusive)

        - `num_aromatic_rings: optional object { max, min }`

          Min/max range constraint for an RDKit molecular descriptor

          - `max: optional number`

            Maximum allowed value (inclusive)

          - `min: optional number`

            Minimum allowed value (inclusive)

        - `num_h_acceptors: optional object { max, min }`

          Min/max range constraint for an RDKit molecular descriptor

          - `max: optional number`

            Maximum allowed value (inclusive)

          - `min: optional number`

            Minimum allowed value (inclusive)

        - `num_h_donors: optional object { max, min }`

          Min/max range constraint for an RDKit molecular descriptor

          - `max: optional number`

            Maximum allowed value (inclusive)

          - `min: optional number`

            Minimum allowed value (inclusive)

        - `num_heteroatoms: optional object { max, min }`

          Min/max range constraint for an RDKit molecular descriptor

          - `max: optional number`

            Maximum allowed value (inclusive)

          - `min: optional number`

            Minimum allowed value (inclusive)

        - `num_rings: optional object { max, min }`

          Min/max range constraint for an RDKit molecular descriptor

          - `max: optional number`

            Maximum allowed value (inclusive)

          - `min: optional number`

            Minimum allowed value (inclusive)

        - `num_rotatable_bonds: optional object { max, min }`

          Min/max range constraint for an RDKit molecular descriptor

          - `max: optional number`

            Maximum allowed value (inclusive)

          - `min: optional number`

            Minimum allowed value (inclusive)

        - `tpsa: optional object { max, min }`

          Min/max range constraint for an RDKit molecular descriptor

          - `max: optional number`

            Maximum allowed value (inclusive)

          - `min: optional number`

            Minimum allowed value (inclusive)

      - `SmartsCustomFilterResponse = object { patterns, type }`

        Filter molecules by custom SMARTS patterns. Molecules matching any pattern are rejected.

        - `patterns: array of string`

          SMARTS patterns. Molecules matching any pattern are rejected.

        - `type: "smarts_custom_filter"`

          - `"smarts_custom_filter"`

      - `SmartsCatalogFilterResponse = object { catalog, type }`

        Filter molecules using a predefined SMARTS catalog of structural alerts.

        - `catalog: "PAINS" or "PAINS_A" or "PAINS_B" or 11 more`

          Predefined SMARTS catalog to apply. PAINS, BRENK, ChEMBL, and NIH catalogs reject known problematic substructures.

          - `"PAINS"`

          - `"PAINS_A"`

          - `"PAINS_B"`

          - `"PAINS_C"`

          - `"BRENK"`

          - `"CHEMBL"`

          - `"CHEMBL_BMS"`

          - `"CHEMBL_Dundee"`

          - `"CHEMBL_Glaxo"`

          - `"CHEMBL_Inpharmatica"`

          - `"CHEMBL_LINT"`

          - `"CHEMBL_MLSMR"`

          - `"CHEMBL_SureChEMBL"`

          - `"NIH"`

        - `type: "smarts_catalog_filter"`

          - `"smarts_catalog_filter"`

      - `SmilesRegexFilterResponse = object { patterns, type }`

        Filter molecules by regex patterns on their SMILES representation.

        - `patterns: array of string`

          Regex patterns applied to SMILES strings. Molecules matching any pattern are rejected.

        - `type: "smiles_regex_filter"`

          - `"smiles_regex_filter"`

- `livemode: boolean`

  Whether this resource was created with a live API key.

- `progress: object { num_molecules_failed, num_molecules_screened, total_molecules_to_screen, 2 more }`

  - `num_molecules_failed: number`

    Number of accepted molecules that reached terminal failure during screening.

  - `num_molecules_screened: number`

    Number of accepted molecules that produced usable screening results.

  - `total_molecules_to_screen: number`

    Total number of molecules accepted into screening after server-side validation and filtering.

  - `latest_result_id: optional string`

    ID of the most recently screened result

  - `rejection_summary: optional object { filtered_count, invalid_count }`

    - `filtered_count: number`

      Number of submitted molecules removed by server-side filtering rules.

    - `invalid_count: number`

      Number of submitted molecules rejected as invalid input.

- `started_at: string`

- `status: "pending" or "running" or "succeeded" or 2 more`

  - `"pending"`

  - `"running"`

  - `"succeeded"`

  - `"failed"`

  - `"stopped"`

- `stopped_at: string`

- `workspace_id: string`

  Workspace ID

- `idempotency_key: optional string`

  Client-provided idempotency key

### Example

```http
curl https://api.boltz.bio/compute/v1/small-molecule/library-screen/$ID/stop \
    -X POST \
    -H "x-api-key: $BOLTZ_API_KEY"
```