MIST is a family of molecular foundation models for molecular property prediction.
The models were pre-trained on SMILES strings from the Enamine REAL Space dataset using the Masked Language Modeling (MLM) objective, then fine-tuned for downstream prediction tasks.
Further information is available in our pre-print on arXiv.
Model Details
Model Description
This fine-tuned MIST variant consists of the MIST-28M encoder finetuned to predict the ionic conductivity of electrolytes (salts in ternary solvent systems).
Fine-tuned MIST models consist of the pretrained MIST model (the encoder), followed by a task network.
The task head constructs a mixture embedding as the sum of the component embeddings weighted by their mole ratios in the mixture:
$$
\begin{align*}
\vec{e}{mix} = \sum{i=0}^{n} x_i \vec{e}_i
\end{align*}
$$
This mixture embedding is used to predict two sets of coefficients.
The first set of coefficients parameterize the VF T relation, which the model uses to learn the dependence of ionic conductivity on temperature.
The second set of coefficients parameterize an empirical correction term used by the model to learn the dependence of ionic conductivity on concentration
Note: SMIRK tokenizers require Rust to be installed. See the Rust installation guide for details.
Property Prediction
python
1from transformers import AutoModel
2from smirk import SmirkTokenizerFast
34model = AutoModel.from_pretrained(5"mist-models/mist-conductivity-27.0M-2mpg8dcd",6 trust_remote_code=True7)89# Make predictions for binary mixture excess properties10smiles_batch =[11{12"solvent_composition":[{"CC1COC(=O)O1":0.9}],13"cation":"[Li+]",14"anion":"F[P-](F)(F)(F)(F)F",15"temperature":298.15,16},17{18"solvent_composition":[19{20"CC1COC(=O)O1":0.3,21"O=C1OCC(F)O1":0.6,22}23],24"cation":"[Li+]",25"anion":"F[P-](F)(F)(F)(F)F",26"temperature":313.0,27},28]29# Returns log ionic conductivity [ln(mS/cm)], pseudo-activation energy Ea [K] and Vogel temperature [K].30results = model.predict(smiles_batch)
Use and Restrictions
Model weights are provided as-is for research purposes only, without guarantees of correctness, fitness for purpose, or warranties of any kind.
Research use only
No redistribution without permission
No commercial use without licensing agreement
Training Details
Training Data
Pretraining
We use the the Enamine REAL Space dataset to pretrain MIST models.
At time of writing, Enamine REAL Space is the largest database of commercially available compounds.
The dataset was constructed using forward synthetic analysis: experimentally validated building blocks were converted into synthons annotated with reactivity features.
Enamine REAL Space was selected as the pretraining dataset since it was the largest database of molecular SMILES at the time of training, it is easily accessible for academic use and molecules relevant to downstream tasks, such as drug candidates, electrolytes, fragrances, live in synthetically accessible regions of chemical space.
where the floats in composition correspond to the mole fraction of the first and second molecules in the smiles_list respectively.
Outputs:
ln conductivity [mS/cm]: log of ionic conductivity in mS/cm
Ea pseudo-activation energy Ea in K.
Tg Vogel temperature in K.
Evaluation
Testing Data
Dataset was split 80/10/10 using a random split.
Metrics
MAE (Mean Absolute Error)
Technical Specifications
Model Architecture and Objective
Encoder: RoBERTa-PreLayerNorm encoder with 8 layers, a hidden size of 512, intermediate size of 2048, 8 attention heads and maximum sequence length of 2048.
Fine-tuning: (MSE) Mean Squared-Error summed for absolute and excess properties
Optimizer:
Pretraining: deepspeed.ops.lamb.FusedLAMB
Fine-tuning: torch.optim.AdamW
Compute Infrastructure
Hardware
This model was pre-trained on 2 NVIDIA A100-SXM4-80GB GPUs in 12 hours 15 minutes.
It was finetuned on 1 NVIDIA A100 GPU.
Software
This model was trained with PyTorchLightning using the DeepSpeed strategy for data distributed parallelism.
Model are exported in a Safetensors format.
Citation
If you use this model in your research, please cite:
bibtex
1@online{MIST,
2 title = {Foundation Models for Discovery and Exploration in Chemical Space},
3 author = {Wadell, Alexius and Bhutani, Anoushka and Azumah, Victor and Ellis-Mohr, Austin R. and Kelly, Celia and Zhao, Hancheng and Nayak, Anuj K. and Hegazy, Kareem and Brace, Alexander and Lin, Hongyi and Emani, Murali and Vishwanath, Venkatram and Gering, Kevin and Alkan, Melisa and Gibbs, Tom and Wells, Jack and Varshney, Lav R. and Ramsundar, Bharath and Duraisamy, Karthik and Mahoney, Michael W. and Ramanathan, Arvind and Viswanathan, Venkatasubramanian},
4 date = {2025-10-20},
5 eprint = {2510.18900},
6 eprinttype = {arXiv},
7 eprintclass = {physics},
8 doi = {10.48550/arXiv.2510.18900},
9 url = {http://arxiv.org/abs/2510.18900},
10}
Model Card Authors
Anoushka Bhutani, Alexius Wadell
Model Card Contact
For questions, issues, or licensing inquiries, please contact Venkat Viswanathan venkvis@umich.edu.