An Agentic Workflow for Legacy HPC Modernization: Converting the Two-Electron-Integral Core of GAMESS

Source

• Source name: arXiv
• Source kind: paper
• Authors / organization: Yuzhong Shen, Masha Sosonkina, Peng Xu, Mark S. Gordon
• Venue: arXiv: cs.AI
• Published: 2026-08-12
• Collected: 2026-08-13
• URL: http://arxiv.org/abs/2608.12249v1
• PDF: https://arxiv.org/pdf/2608.12249v1
• DOI: UNKNOWN
• Registry group: academic_apis_and_preprints
• Evidence role: canonical_academic_index
• Language: en
• Country / region: UNKNOWN

Plain-Language Brief

The authors propose an agentic workflow for large-scale modernization of legacy Fortran code, specifically demonstrating it on the two-electron-integral routines of GAMESS (a 48-year old quantum chemistry software). The workflow involves three specialized agent roles and human oversight. They were able to convert twelve source files totaling 56,448 lines and 225 subroutines from Fortran 77 to Fortran 2008, passing a 51-test validation battery and showing zero chemistry-relevant differences across 612 test runs.

What the Document Says

• The authors propose an agentic workflow for large-scale modernization of legacy Fortran code.
• They apply this workflow in a case study, converting the two-electron-integral routines of GAMESS from fixed-form Fortran 77 to free-form Fortran 2008.
• The scope of their work was twelve source files, 56,448 lines, and 225 subroutines.

Key Concepts Mentioned

• agentic workflow
• legacy Fortran modernization
• GAMESS
• two-electron-integral routines

Claims Made by the Document

• The proposed workflow can handle production-scale code modernization.
• The agents were able to convert the GAMESS source files successfully.

Evidence Used

• The authors' description of their workflow and its application.
• The details about the conversion and testing of the GAMESS source files.

Methods / Approach

UNKNOWN

Limitations Stated by the Authors

UNKNOWN

Limitations Noted by the Agent

Agent interpretation — not from the source.

UNKNOWN

Open Questions

UNKNOWN

Notes for Future Q&A

May include interpretation. Labeled where it does.

UNKNOWN

Raw Abstract / Excerpt

Modernizing legacy Fortran is a problem of volume: the transformations are individually routine, but the codebases can be enormous, and across much of computational science the work simply goes undone. We propose an agentic workflow that takes this work on at production scale, and we set out to measure how far such delegation can reach. In this work, three prompt-specialized agent roles operate under a version-controlled specification that the agents themselves authored and revised, while humans hold a small number of gates. The arrangement is kept safe by an exact verification oracle inherited from the domain, and the boundary of safe delegation lies exactly where that oracle stops seeing. We apply the proposed workflow in a case study, converting the two-electron-integral routines of GAMESS (General Atomic and Molecular Electronic Structure System), a mature quantum-chemistry package with a 48-year development history, from fixed-form Fortran 77 to free-form Fortran 2008. The scope of this work was twelve source files, 56,448 lines, and 225 subroutines for computing electron repulsion integrals. The agents ran as three Claude Code roles in isolated worktrees, and the work spanned four Claude model generations. Because the GAMESS group ships a standard test suite whose printed energies its user community treats as canonical, we could adopt bit-for-bit reproduction of those energies as the merge criterion, where a deviation in the twelfth decimal place counts as a failure rather than drift. All twelve source files pass a 51-test validation battery comprising the 49 standard GAMESS tests and two additional calculations, and across 612 test runs the number of chemistry-relevant differences is zero, and every file also passes the Jenkins tests that are used for continuous integration.