Rowan: Cloud-Native Molecular-Modeling and Drug-Design Workflows

Overview

Rowan is a cloud-native workflow platform for molecular simulation, medicinal chemistry, and structure-based design. Its Python API exposes a unified interface for small-molecule modeling, property prediction, docking, molecular dynamics, and AI structure workflows.

Use Rowan when you want to run medicinal-chemistry or molecular-design workflows programmatically without maintaining local HPC infrastructure, GPU provisioning, or a collection of separate modeling tools. The service manages hosted compute and results; available workflows depend on the account.

When to use Rowan

Rowan is a good fit for:

• Quantum chemistry, semiempirical methods, or neural network potentials
• Batch property prediction (pKa, descriptors, permeability, solubility)
• Conformer and tautomer ensemble generation
• Docking workflows (single-ligand, analogue series, pose refinement)
• Protein-ligand cofolding and MSA generation
• Multi-step chemistry pipelines (e.g., tautomer search → docking → pose analysis)
• Batch medicinal-chemistry campaigns where you need consistent, scalable infrastructure

Rowan is not the right fit for:

• Simple molecular I/O (use RDKit directly)
• Methods or element/charge regimes outside the selected engine's documented support

Quick start

uv pip install "rowan-python==3.2.0"

import rowan
# Reads ROWAN_API_KEY from the environment.

# Descriptors require a 3D Molecule, not a bare SMILES string.
mol = rowan.Molecule.from_smiles("CC(=O)Oc1ccccc1C(=O)O")
wf = rowan.submit_descriptors_workflow(mol, name="aspirin")
result = wf.result()

print(result.descriptors["MW"])       # exact/monoisotopic mass
print(result.descriptors["SLogP"])
print(result.descriptors["TopoPSA"])  # topological PSA

This submits a hosted calculation and consumes credits. Examples target rowan-python 3.2.0, reviewed 2026-09-30 against the released SDK and official reference. Local schema/serialization smoke tests used stjames 0.0.279. Hosted examples are illustrative: no authenticated workflows were run for this refresh. Lock both package versions for a reproducible campaign.

Installation

uv pip install "rowan-python==3.2.0"
# Lock dependencies in your own environment; do not install the unrelated "rowan" package.

Authentication and account access

Authentication

Set an API key via environment variable (recommended):

export ROWAN_API_KEY="your_api_key_here"

Or set directly in Python:

import rowan
rowan.api_key = "your_api_key_here"

Verify authentication:

import rowan
user = rowan.whoami()  # Returns user info if authenticated
print(f"User: {user.email}")
print(f"Credits available: {user.credits_available_string()}")
print(user.enabled_workflows)  # Account-specific backend workflow slugs

Molecule input formats

Use SMILES for topology-based methods and real 3D structures for geometry-based methods. SMARTS is a substructure-query language, not a general workflow molecule input; convert InChI with a chemistry toolkit before passing a supported input. Record stereochemistry, charge, protonation state, and the original identifier. Canonicalization alone does not resolve these scientific choices.

SMILES strings versus molecule objects

• pKa: starling and chemprop_nevolianis2025 require a SMILES string; gxtb_wagen2026 (default) and aimnet2_wagen2024 require coordinates.
• Conformer search: SMILES works with OpenConf (default) or ETKDG; CREST/MCMM require a 3D molecule.
• Membrane permeability: gnn-mtl requires SMILES; pypermm requires a 3D molecule.
• ADMET, LogP, macropKa, and solubility are SMILES-based; pose-analysis MD needs ligand SMILES and a protein complex containing its bound pose.
• Descriptors, tautomers, docking, analogue docking, BDE, NMR, and Fukui need a rowan.Molecule, stjames.Molecule, or RDKit molecule with a conformer. Chem.MolFromSmiles() alone has no coordinates. Generate them explicitly with rowan.Molecule.from_smiles() or import an existing geometry. For analogue docking, preserve the reference pose in the receptor's coordinate frame.

Tip: Use RDKit to validate SMILES before submission:

from rdkit import Chem
smiles = "CCO"
mol = Chem.MolFromSmiles(smiles)
if mol is None:

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