EvoMD-LLM: Learning the Language of Species Evolution in Reactive Molecular Dynamics
Paper · 2026 · Zhichen Tang, Zhengzheng Dang, Yulin Chen et al.
Summary
LLMs handle static chemistry well, but they have trouble capturing how reactive systems change over time. EvoMD-LLM addresses this by recasting reactive molecular dynamics (MD) as a symbolic sequence task. Raw trajectories are converted into a sequence of species events:
- an ab initio bond-order criterion identifies which atoms are bonded in each frame;
- connected components of the resulting graph are turned into molecular formulas;
- each formula is paired with the time it persists.
Each formula is kept as one indivisible token rather than split into characters. A duration token is placed next to every species, an idea the authors call temporal scaffolding and compare to run-length encoding. The duration acts as a signal of kinetic stability. An instruction-tuned autoregressive LLM is then fine-tuned on sliding windows of these events. The same model handles several prediction tasks, including forecasting forward and inferring backward.
On a Mo-S chemical vapor deposition (CVD) system, the model reaches up to 66.14% accuracy and beats both sequential neural networks and language-based baselines. Duration tokens noticeably cut down on invalid or hallucinated species. The model also produces chemically plausible explanations for its predictions, even though it was never trained on such explanations. This suggests LLMs can serve as general learners of time-resolved simulation data.
Key points
- Events are band-pass filtered to durations between 10 and 500 ps. Each training example uses a context of 3–5 past events to predict the next one.
- Two-dimensional stratified sampling over species identity and duration bins (short, medium, long) counters the long-tail species distribution.
- Ablations show that temporal scaffolding raises accuracy and reduces outputs of invalid molecules. The best reported accuracy is 66.14%.
- Qwen3 was used as an automated judge to score the qualitative explanations. Example cases cover Mo–O/S species such as MoS, MoS₃ and MoS₅.
- Stated limitations:
- evaluation covers only the Mo-S system;
- errors accumulate in multi-step (N-step) prediction;
- the symbolic representation loses fine-grained geometry;
- explanations can be plausible yet ungrounded.
Institutions
Fields, topics and concepts
📚 Shelves 6The field of science this work belongs to (OpenAlex fields).Physics and Astronomy · 52 worksStatistical and Nonlinear Physics · 47 worksMaterials Science · 31 worksMaterials Chemistry · 31 worksChemistry · 4 worksPhysical and Theoretical Chemistry · 4 works
🧭 Topics 1Research subjects and languages the work is about.Language models & pretraining · 3,894 works
Cite
Cite as Zhichen Tang, Zhengzheng Dang, Yulin Chen, Jixin Wu, Haiwen Li and Yanming Wang. 2026. EvoMD-LLM: Learning the Language of Species Evolution in Reactive Molecular Dynamics. Findings of the Association for Computational Linguistics: ACL 2026.
@inproceedings{tang2026evomd,
title = {{EvoMD-LLM: Learning the Language of Species Evolution in Reactive Molecular Dynamics}},
author = {Zhichen Tang, Zhengzheng Dang, Yulin Chen, Jixin Wu, Haiwen Li and Yanming Wang},
booktitle = {Findings of the Association for Computational Linguistics: ACL 2026},
year = {2026},
doi = {10.18653/v1/2026.findings-acl.1947},
url = {https://doi.org/10.18653/v1/2026.findings-acl.1947}
}References
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