# mRNA forcefields issue

**URL:** <https://gromacs.bioexcel.eu/t/mrna-forcefields-issue/12734>\
**Category:** User discussions\
**Tags:** forcefield\
**Created:** [October 5, 2025, 11:41am UTC](https://gromacs.bioexcel.eu/t/mrna-forcefields-issue/12734 "2025-10-05T11:41:06Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![ASSIM](https://avatars.discourse-cdn.com/v4/letter/a/8c91f0/32.png) [@ASSIM](https://gromacs.bioexcel.eu/u/ASSIM)\
**Post date:** [October 5, 2025, 11:41am UTC](https://gromacs.bioexcel.eu/t/mrna-forcefields-issue/12734/1 "2025-10-05T11:41:06Z")

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Dear GROMACS Community

Please help me with an issue i am facing in applying forcefields to mRNA. I am using 8OIV pdb. It has 5’ mRNA cap (m7GTP) linked with triphosphate bridge and then GAAA nucleotides (chain name GTG). The problem is charmm-gui cannot recognize m7GTP, however when i changed the name to 7MG, other nucleotides get lost in solution builder. Or if I try to save RNA (GAAA) m7GTP get lost in the solution builder. How can i use use this complete mRNA patch (m7GTP-GAAA) for my GROMACS simulation?  
Thanks in advance for helping.

Assim Verma