ML Conformer Generator

ML Conformer Generator is a tool for spatially-aware molecule generation with an Equivariant Diffusion Model (EDM) and a Graph Convolutional Network (GCN). It is designed to generate 3D molecular conformations that are both chemically valid and spatially similar to a reference shape.

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Molecule Generation in Action

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Supported features

• Shape-guided molecular generation

  Generate novel molecules that conform to arbitrary 3D shapes—such as protein binding pockets or custom-defined spatial regions.

• Objective-guided Generation

  Use reinforcement learning (RL) to steer molecular generation toward higher-scoring candidates, with support for custom scoring functions.

• Reference-based conformer similarity

  Create molecules conformations of which closely resemble a reference structure, supporting scaffold-hopping and ligand-based design workflows.

• Fragment-based inpainting

  Fix specific substructures or fragments within a molecule and complete or grow the rest in a geometrically consistent manner.

• Inertial Fragment Matching

  Generate molecules fragment-by-fragment by leveraging the physical properties of the shape descriptor, improving both shape similarity and chemical validity.

Citation

If you use MLConfGen in your research, please cite:

Denis Sapegin, Fedor Bakharev, Dmitry Krupenya, Azamat Gafurov, Konstantin Pildish, and Joseph C. Bear.
Moment of inertia as a simple shape descriptor for diffusion-based shape-constrained molecular generation.
Digital Discovery, 2025. DOI: 10.1039/D5DD00318K

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Installation

1. Install the package for your preferred backend:

   • pip install mlconfgen[torch] — use the PyTorch-based inference pipeline

   • pip install mlconfgen[onnx] — use the torch-free ONNX runtime version

2. Load the weights from Huggingface

https://huggingface.co/Membrizard/ml_conformer_generator

edm_moi_chembl_15_39.pt

adj_mat_seer_chembl_15_39.pt

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🐍 Python API

See interactive examples: ./python_api_demo.ipynb

from rdkit import Chem
from mlconfgen import MLConformerGenerator, evaluate_samples

model = MLConformerGenerator(
                             edm_weights="./edm_moi_chembl_15_39.pt",
                             adj_mat_seer_weights="./adj_mat_seer_chembl_15_39.pt",
                             diffusion_steps=100,
                            )

reference = Chem.MolFromMolFile('./assets/demo_files/ceyyag.mol')

samples = model.generate_conformers(reference_conformer=reference, n_samples=20, variance=2)

aligned_reference, std_samples = evaluate_samples(reference, samples)

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🚀 Overview

This solution employs:

• Equivariant Diffusion Model (EDM) [1]: For generating atom coordinates and types under a shape constraint.
• Graph Convolutional Network (GCN) [2]: For predicting atom adjacency matrices.
• Deterministic Standardization Pipeline: For refining and validating generated molecules.

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🧠 Model Training

• Trained on 1.6 million compounds from the ChEMBL database.
• Filtered to molecules with 15–39 heavy atoms.
• Supported elements: H, C, N, O, F, P, S, Cl, Br.

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🧪 Standardization Pipeline

The generated molecules are post-processed through the following steps:

• Largest Fragment picker
• Valence check
• Kekulization
• RDKit sanitization
• Constrained Geometry optimization via MMFF94 Molecular Dynamics

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📏 Evaluation Pipeline

Aligns and Evaluates shape similarity between generated molecules and a reference using Shape Tanimoto Similarity [3] via Gaussian Molecular Volume overlap.

Hydrogens are ignored in both reference and generated samples for this metric.

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📊 Performance (100 Denoising Steps)

Tested on 100,000 samples using 1,000 CCDC Virtual Screening [4] reference compounds.

General Overview

• ⏱ Avg time to generate 50 valid samples: 11.46 sec (NVIDIA H100) (100 samples batch)
• ⚡️ Generation speed: 4.18 valid molecules/sec (100 samples batch)
• 💾 GPU memory (per generation thread): Up to 14.0 GB (float16 39 atoms 100 samples)
• 📐 Avg Shape Tanimoto Similarity: 53.32% (Basic generation) - 69.97% (Inertial Fragment Matching)
• 🎯 Max Shape Tanimoto Similarity: 99.69%
• 🔬 Avg Chemical Tanimoto Similarity (2-hop 2048-bit Morgan Fingerprints): 10.87%
• 🧬 % Chemically novel (vs. training set): 99.84%
• ✔️ % Valid molecules (post-standardization): 48% (ML Bond Prediction) - 93% (OpenBabel bond prediction)
• 🔁 % Unique molecules in generated set: 99.94%
• 📎 Fréchet Fingerprint Distance (2-hop 2048-bit Morgan Fingerprints):
  • To ChEMBL: 4.13
  • To PubChem: 2.64
  • To ZINC (250k): 4.95

PoseBusters [5] validity check results:

Overall stats:

• PB-valid molecules: 91.33 %

Detailed Problems:

• position: 0.01 %
• mol_pred_loaded: 0.0 %
• sanitization: 0.01 %
• inchi_convertible: 0.01 %
• all_atoms_connected: 0.0 %
• bond_lengths: 0.24 %
• bond_angles: 0.70 %
• internal_steric_clash: 2.31 %
• aromatic_ring_flatness: 3.34 %
• non-aromatic_ring_non-flatness: 0.27 %

Synthesizability of the generated compounds

SA Score [6]

1 (easy to make) - 10 (very difficult to make)

Average SA Score: 3.18

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RL Fine Tuning

MLConformerGenerator supports objective-guided reinforcement learning (RL) fine-tuning, allowing you to steer the generated molecular distribution toward molecules that better match your desired properties.

Scoring functions are fully customizable. The only requirement is that they accept a list of RDKit Mol objects and return a list of scores in the range [0, 1].

A scoring function should follow this interface:

from rdkit import Chem

def scoring_function(mols: list[Chem.Mol | None]) -> list[float]:
    ...

Example: RL fine-tuning

Note

If scoring_function is None, a default scoring function enforcing validity is applied for RL.

from rdkit import Chem
from mlconfgen import MLConformerGenerator

model = MLConformerGenerator(
                             edm_weights="./edm_moi_chembl_15_39.pt",
                             adj_mat_seer_weights="./adj_mat_seer_chembl_15_39.pt",
                             diffusion_steps=10,
                            )

reference = Chem.MolFromMolFile('./assets/demo_files/ceyyag.mol')

model.fine_tune(
                  reference_conformer=reference,
                  variance=1,
                  n_epochs=20,
                  sigma=60.0,
                  lambda_edm_adapter=1.5,
                  temperature=1.5,
                  n_samples_per_mol=16,
                  eval_every=5,
                  save_dir="./rl_checkpoints"
)

Fine-tuning produces both the best and the latest checkpoints, which can later be loaded into the model:

from mlconfgen import MLConformerGenerator

model = MLConformerGenerator(
                             edm_weights="./edm_moi_chembl_15_39.pt",
                             adj_mat_seer_weights="./adj_mat_seer_chembl_15_39.pt",
                             finetune_checkpoint = "./finetune_checkpoint.pt",
                             diffusion_steps=10,
                            )

# Or

model.load_finetune_checkpoint("./finetune_checkpoint.pt")

REINVENT4 compatibility

The RL fine-tuning pipeline is compatible with scoring functions from REINVENT4. If REINVENT4 is installed, you can use ReinventScoreWrapper to load a REINVENT4 scoring configuration and use MLConfGen as a spatially-aware molecule generator.

For working examples, see rl_fine_tuning_demo.ipynb.

from rdkit import Chem
from mlconfgen import MLConformerGenerator
from mlconfgen.rl_fine_tuning.reinvent_score_wrapper import ReinventScoreWrapper

model = MLConformerGenerator(
                             edm_weights="./edm_moi_chembl_15_39.pt",
                             adj_mat_seer_weights="./adj_mat_seer_chembl_15_39.pt",
                             diffusion_steps=10,
                            )

reference = Chem.MolFromMolFile('./assets/demo_files/ceyyag.mol')
scoring_function = ReinventScoreWrapper("./assets/demo_files/scoring_config.toml")

model.fine_tune(
                  scoring_function=scoring_function, 
                  reference_conformer=reference,
                  variance=1,
                  n_epochs=100,
                  train_batch_size=128,
                  eval_batch_size=128,
                  learning_rate= 8e-5,
                  sigma=128.0,
                  lambda_edm_adapter=1.5,
                  lambda_edm_reg=0.2,
                  temperature=1.5,
                  n_samples_per_mol=32,
                  eval_every=5,
                  save_dir="./rl_checkpoints_reinvent",

)

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Generation Examples

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💾 Access & Licensing

The Python package and inference code are available on GitHub under Apache 2.0 License

https://github.com/Membrizard/ml_conformer_generator

The trained model Weights are available at

https://huggingface.co/Membrizard/ml_conformer_generator

And are licensed under CC BY-NC-ND 4.0

The usage of the trained weights for any profit-generating activity is restricted.

For commercial licensing and inference-as-a-service, contact: Denis Sapegin

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ONNX Inference:

For torch Free inference an ONNX version of the model is present.

Weights of the model in ONNX format are available at:

https://huggingface.co/Membrizard/ml_conformer_generator

egnn_chembl_15_39.onnx

adj_mat_seer_chembl_15_39.onnx

from mlconfgen import MLConformerGeneratorONNX
from rdkit import Chem

model = MLConformerGeneratorONNX(
                                 egnn_onnx="./egnn_chembl_15_39.onnx",
                                 adj_mat_seer_onnx="./adj_mat_seer_chembl_15_39.onnx",
                                 diffusion_steps=100,
                                )

reference = Chem.MolFromMolFile('./assets/demo_files/yibfeu.mol')
samples = model.generate_conformers(reference_conformer=reference, n_samples=20, variance=2)

Install ONNX GPU runtime (if needed): pip install onnxruntime-gpu

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Export to ONNX

An option to compile the model to ONNX is provided

requires onnxscript==0.2.2

pip install onnxscript

from mlconfgen import MLConformerGenerator
from onnx_export import export_to_onnx

model = MLConformerGenerator()
export_to_onnx(model)

This compiles and saves the ONNX files to: ./

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Testing

To execute all tests (including slow generation ones)

pytest -v tests

To bypass generation tests

pytest -v tests -m "not slow"

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Streamlit App

Running

• Move the trained PyTorch weights into ./streamlit_app

./streamlit_app/edm_moi_chembl_15_39.pt

./streamlit_app/adj_mat_seer_chembl_15_39.pt

• Install the dependencies pip install -r ./streamlit_app/requirements.txt

• Bring the app UI up:

  cd ./streamlit_app
  streamlit run app.py
  

Streamlit App Development

1. To enable development mode for the 3D viewer (stspeck), set _RELEASE = False in ./streamlit/stspeck/__init__.py.

2. Navigate to the 3D viewer frontend and start the development server:

   cd ./frontend/speck/frontend
   npm run start
   

   This will launch the dev server at http://localhost:3001

3. In a separate terminal, run the Streamlit app from the root frontend directory:

   cd ./streamlit_app
   streamlit run app.py
   

4. To build the production version of the 3D viewer, run:

   cd ./streamlit_app/stspeck/frontend
   npm run build