How Well Do Large-Scale Chemical Language Models Transfer to Downstream Tasks?

Fuente: arXiv
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Auteurs principaux: Sagawa, Tatsuya, Kojima, Ryosuke
Format: Preprint
Publié: 2026
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author Sagawa, Tatsuya
Kojima, Ryosuke
author_facet Sagawa, Tatsuya
Kojima, Ryosuke
contents Chemical Language Models (CLMs) pre-trained on large scale molecular data are widely used for molecular property prediction. However, the common belief that increasing training resources such as model size, dataset size, and training compute improves both pretraining loss and downstream task performance has not been systematically validated in the chemical domain. In this work, we evaluate this assumption by pretraining CLMs while scaling training resources and measuring transfer performance across diverse molecular property prediction (MPP) tasks. We find that while pretraining loss consistently decreases with increased training resources, downstream task performance shows limited improvement. Moreover, alternative metrics based on the Hessian or loss landscape also fail to estimate downstream performance in CLMs. We further identify conditions under which downstream performance saturates or degrades despite continued improvements in pretraining metrics, and analyze the underlying task dependent failure modes through parameter space visualizations. These results expose a gap between pretraining based evaluation and downstream performance, and emphasize the need for model selection and evaluation strategies that explicitly account for downstream task characteristics.
format Preprint
id arxiv_https___arxiv_org_abs_2602_11618
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle How Well Do Large-Scale Chemical Language Models Transfer to Downstream Tasks?
Sagawa, Tatsuya
Kojima, Ryosuke
Machine Learning
Quantitative Methods
Chemical Language Models (CLMs) pre-trained on large scale molecular data are widely used for molecular property prediction. However, the common belief that increasing training resources such as model size, dataset size, and training compute improves both pretraining loss and downstream task performance has not been systematically validated in the chemical domain. In this work, we evaluate this assumption by pretraining CLMs while scaling training resources and measuring transfer performance across diverse molecular property prediction (MPP) tasks. We find that while pretraining loss consistently decreases with increased training resources, downstream task performance shows limited improvement. Moreover, alternative metrics based on the Hessian or loss landscape also fail to estimate downstream performance in CLMs. We further identify conditions under which downstream performance saturates or degrades despite continued improvements in pretraining metrics, and analyze the underlying task dependent failure modes through parameter space visualizations. These results expose a gap between pretraining based evaluation and downstream performance, and emphasize the need for model selection and evaluation strategies that explicitly account for downstream task characteristics.
title How Well Do Large-Scale Chemical Language Models Transfer to Downstream Tasks?
topic Machine Learning
Quantitative Methods
url https://arxiv.org/abs/2602.11618