@inproceedings{cao-etal-2026-molecule,
title = "Molecule Generation through Reasoning with Large Language Models",
author = "Cao, Congfeng and
Wu, Di and
Zhang, Zhi and
Huang, Jia-Hong and
Bloem, Jelke and
Sima{'}an, Khalil",
editor = "Zhang, Yue and
Xu, Ruifeng and
Purwarianti, Ayu and
Rong, Tong and
Suzuki, Jun",
booktitle = "Findings of the {A}ssociation for {C}omputational {L}inguistics: {IJCNLP}-{AACL} 2026",
month = nov,
year = "2026",
address = "Hengqin, China",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.findings-aacl.195/",
pages = "3862--3879",
ISBN = "979-8-89176-444-6",
abstract = "Molecule generation is significant for its potential in scientific discovery and practical applications. Recent attempts often frame this task as a *translation* problem from molecular caption to structural representation, such as SMILES. This paper first examines the feasibility of modeling the task as a reasoning process with large language models (LLMs), generating higher-quality molecules through structural decomposition and recombination within curated Chain-of-Thought (CoT). We then introduce a workflow for curating accurate CoT data, incorporating both machine and expert verification. Lastly, we demonstrate that with a limited dataset of 4,213 curated samples, namely **MolCoT4K**, we elicit strong reasoning capabilities for molecule generation in open-source LLMs such as Qwen2.5-7B, achieving state-of-the-art exact match accuracy over strong open-source baselines (e.g., MolT5 and LlaSMol) as well as advanced commercial LLMs like GPT-4o. Moreover, the resulting model, **MolGeneration**, attains a Pass@16 exact match accuracy of 48.46{\%}, highlighting its strong potential for real-world experimental applications when supported by a feasible external verifier or chemistry experts. Our analysis shows that the correctness of the CoT path is crucial, while reasoning ability primarily enhances accuracy in fine-grained molecule generation."
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<abstract>Molecule generation is significant for its potential in scientific discovery and practical applications. Recent attempts often frame this task as a *translation* problem from molecular caption to structural representation, such as SMILES. This paper first examines the feasibility of modeling the task as a reasoning process with large language models (LLMs), generating higher-quality molecules through structural decomposition and recombination within curated Chain-of-Thought (CoT). We then introduce a workflow for curating accurate CoT data, incorporating both machine and expert verification. Lastly, we demonstrate that with a limited dataset of 4,213 curated samples, namely **MolCoT4K**, we elicit strong reasoning capabilities for molecule generation in open-source LLMs such as Qwen2.5-7B, achieving state-of-the-art exact match accuracy over strong open-source baselines (e.g., MolT5 and LlaSMol) as well as advanced commercial LLMs like GPT-4o. Moreover, the resulting model, **MolGeneration**, attains a Pass@16 exact match accuracy of 48.46%, highlighting its strong potential for real-world experimental applications when supported by a feasible external verifier or chemistry experts. Our analysis shows that the correctness of the CoT path is crucial, while reasoning ability primarily enhances accuracy in fine-grained molecule generation.</abstract>
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%0 Conference Proceedings
%T Molecule Generation through Reasoning with Large Language Models
%A Cao, Congfeng
%A Wu, Di
%A Zhang, Zhi
%A Huang, Jia-Hong
%A Bloem, Jelke
%A Sima’an, Khalil
%Y Zhang, Yue
%Y Xu, Ruifeng
%Y Purwarianti, Ayu
%Y Rong, Tong
%Y Suzuki, Jun
%S Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026
%D 2026
%8 November
%I Association for Computational Linguistics
%C Hengqin, China
%@ 979-8-89176-444-6
%F cao-etal-2026-molecule
%X Molecule generation is significant for its potential in scientific discovery and practical applications. Recent attempts often frame this task as a *translation* problem from molecular caption to structural representation, such as SMILES. This paper first examines the feasibility of modeling the task as a reasoning process with large language models (LLMs), generating higher-quality molecules through structural decomposition and recombination within curated Chain-of-Thought (CoT). We then introduce a workflow for curating accurate CoT data, incorporating both machine and expert verification. Lastly, we demonstrate that with a limited dataset of 4,213 curated samples, namely **MolCoT4K**, we elicit strong reasoning capabilities for molecule generation in open-source LLMs such as Qwen2.5-7B, achieving state-of-the-art exact match accuracy over strong open-source baselines (e.g., MolT5 and LlaSMol) as well as advanced commercial LLMs like GPT-4o. Moreover, the resulting model, **MolGeneration**, attains a Pass@16 exact match accuracy of 48.46%, highlighting its strong potential for real-world experimental applications when supported by a feasible external verifier or chemistry experts. Our analysis shows that the correctness of the CoT path is crucial, while reasoning ability primarily enhances accuracy in fine-grained molecule generation.
%U https://aclanthology.org/2026.findings-aacl.195/
%P 3862-3879
Markdown (Informal)
[Molecule Generation through Reasoning with Large Language Models](https://aclanthology.org/2026.findings-aacl.195/) (Cao et al., Findings 2026)
ACL