# QM/MM CP2K- isotope

**URL:** <https://ask.bioexcel.eu/t/qm-mm-cp2k-isotope/4091>\
**Category:** QM/MM for Biomolecular Simulation\
**Created:** [February 3, 2023, 4:20pm UTC](https://ask.bioexcel.eu/t/qm-mm-cp2k-isotope/4091 "2023-02-03T16:20:08Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![isilayozturk](https://dub1.discourse-cdn.com/flex013/user_avatar/ask.bioexcel.eu/isilayozturk/32/451_2.png) [@isilayozturk](https://ask.bioexcel.eu/u/isilayozturk)\
**Post date:** [February 3, 2023, 4:20pm UTC](https://ask.bioexcel.eu/t/qm-mm-cp2k-isotope/4091/1 "2023-02-03T16:20:08Z")

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Can we specifically identify the metal of isotope when doing QM/MM in CP2K?

Best!

Işılay

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**Author:** ![dmorozov](https://avatars.discourse-cdn.com/v4/letter/d/dec6dc/32.png) [@dmorozov](https://ask.bioexcel.eu/u/dmorozov)\
**Post date:** [February 15, 2023, 8:42am UTC](https://ask.bioexcel.eu/t/qm-mm-cp2k-isotope/4091/2 "2023-02-15T08:42:35Z")

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Hi Isilay,

Isotope atom has different mass, it does not affect QM calculation itself.  
mass of atoms could be changed in the GROMACS topology file mass column:

![image](https://europe1.discourse-cdn.com/flex013/uploads/bioexcel/original/1X/69bd60bc86d7ec69c7578421e130a8424bfd3996.png)

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<div class="post-metadata">

**Author:** ![isilayozturk](https://dub1.discourse-cdn.com/flex013/user_avatar/ask.bioexcel.eu/isilayozturk/32/451_2.png) [@isilayozturk](https://ask.bioexcel.eu/u/isilayozturk)\
**Post date:** [February 15, 2023, 9:25am UTC](https://ask.bioexcel.eu/t/qm-mm-cp2k-isotope/4091/3 "2023-02-15T09:25:00Z")

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Many Thanks!!

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**Author:** ![isilayozturk](https://dub1.discourse-cdn.com/flex013/user_avatar/ask.bioexcel.eu/isilayozturk/32/451_2.png) [@isilayozturk](https://ask.bioexcel.eu/u/isilayozturk)\
**Post date:** [November 1, 2023, 12:54am UTC](https://ask.bioexcel.eu/t/qm-mm-cp2k-isotope/4091/4 "2023-11-01T00:54:27Z")

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Hello all,

I am trying to apply QM/MM with Gromacs+CP2K interface but I have error… I have Gallium and basic, N,O,H,C atoms. CP2K part is giving error. during energy minimization part. Probably gromacs part has problem as well… I am sharing with you my input and outputs. I didn’t understand any thing from error… Thank u in advance… (P.S. first I used to amber22 for creating forcefield parameters for the gallium with metal center parameter builder (MCPB.py). I converted amber parameters with acpype.py for gromacs))

I uploaded my files to google driver ıf you give some feedback. I will be so glad.

[https://drive.google.com/drive/folders/1Vn5dLD-BWxsSJ7-5\_XWxibxH41EFcSLg?usp=drive\_link](https://drive.google.com/drive/folders/1Vn5dLD-BWxsSJ7-5_XWxibxH41EFcSLg?usp=drive_link)