# Segmentation fault or cuda error #700 during eABF/WTM-eABF calculations

**URL:** https://gromacs.bioexcel.eu/t/segmentation-fault-or-cuda-error-700-during-eabf-wtm-eabf-calculations/12099
**Category:** User discussions
**Tags:** mdrun, gpu, free-energy
**Created:** [May 17, 2025, 9:58am UTC](https://gromacs.bioexcel.eu/t/segmentation-fault-or-cuda-error-700-during-eabf-wtm-eabf-calculations/12099 "2025-05-17T09:58:01Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![kaiyuan](https://avatars.discourse-cdn.com/v4/letter/k/47e85d/32.png) [@kaiyuan](https://gromacs.bioexcel.eu/u/kaiyuan)
#### Post date: [May 17, 2025, 9:58am UTC](https://gromacs.bioexcel.eu/t/segmentation-fault-or-cuda-error-700-during-eabf-wtm-eabf-calculations/12099/1 "2025-05-17T09:58:01Z")

</div>

GROMACS version: 2025.1  
GROMACS modification: No

Hi, I’m trying to calculate the dimerization free energy of a hydrophobic molecule that contains a small graphene nanosheet and several side chains. I used the WTM-eABF method of the colvars module.  
Two CVs were adopted: 1, the distance between COMs of the two molecules; 2, the torsion angle between the two molecules.  
I tried several different MtD parameters (hillwidth, hillweight, biastemperature) and I also tried to use the eABF method solely, however, the simulations always got crashed after several tens of nanoseconds. Sometimes I got the segmentation fault error, and at other times it’s cuda error#700. The mdp and colvars configuration files were attached below.

I don’t know what other settings I can still modify now. I would appreciate any suggestions. Thanks a lot.  
[mdNPT.mdp](https://gromacs.bioexcel.eu/uploads/short-url/6DlGpsz4eFVIJpJVdCoAAQC64dm.mdp) (1.9 KB)  
[colvars.txt](https://gromacs.bioexcel.eu/uploads/short-url/k6B5dCnY58emKKx1sn6yB6r7WZi.txt) (1.7 KB)