# Equilibration eeror

**URL:** <https://gromacs.bioexcel.eu/t/equilibration-eeror/10213>\
**Category:** User discussions\
**Created:** [September 23, 2024, 10:09am UTC](https://gromacs.bioexcel.eu/t/equilibration-eeror/10213 "2024-09-23T10:09:57Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![AnanyaC](https://avatars.discourse-cdn.com/v4/letter/a/8797f3/32.png) [@AnanyaC](https://gromacs.bioexcel.eu/u/AnanyaC)\
**Post date:** [September 23, 2024, 10:09am UTC](https://gromacs.bioexcel.eu/t/equilibration-eeror/10213/1 "2024-09-23T10:09:57Z")

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GROMACS version:  
GROMACS modification: Yes/No  
I am trying to simulate a model system I have modelled myself. The steps till NVT-equilibration are running fine. But when trying to do npt equilibration its throwing error like  
step 600: timed with pme grid 128 128 128, coulomb cutoff 2.100: 4641.1 M-cycles  
step 800: timed with pme grid 112 112 112, coulomb cutoff 2.272: 5541.5 M-cycles  
step 1000: timed with pme grid 120 120 120, coulomb cutoff 2.120: 4874.3 M-cycles  
Constraint error in algorithm Lincs at step 1076  
Wrote pdb files with previous and current coordinates  
Constraint error in algorithm Lincs at step 1078  
Wrote pdb files with previous and current coordinates  
Constraint error in algorithm Lincs at step 1079  
Wrote pdb files with previous and current coordinates

* * *

Program: gmx mdrun, version 2022.3  
Source file: src/gromacs/gpu\_utils/cudautils.cuh (line 190)

Fatal error:  
Unexpected cudaStreamQuery failure. CUDA error #700 (cudaErrorIllegalAddress):  
an illegal memory access was encountered.

I made some changes, the error was gone but the equilibration stops at 0 checkpoint.  
Can someone throw some insights please.

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<div class="post-metadata">

**Author:** ![MagnusL](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/magnusl/32/2380_2.png) [@MagnusL](https://gromacs.bioexcel.eu/u/MagnusL)\
**Post date:** [September 26, 2024, 7:13am UTC](https://gromacs.bioexcel.eu/t/equilibration-eeror/10213/2 "2024-09-26T07:13:37Z")

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It is almost certainly a system explosion. Start by reading [Terminology - GROMACS 2024.3 documentation](https://manual.gromacs.org/current/user-guide/terminology.html#blowing-up) and see if any of the recommendations help you.

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**Author:** ![AnanyaC](https://avatars.discourse-cdn.com/v4/letter/a/8797f3/32.png) [@AnanyaC](https://gromacs.bioexcel.eu/u/AnanyaC)\
**Post date:** [October 1, 2024, 5:18am UTC](https://gromacs.bioexcel.eu/t/equilibration-eeror/10213/3 "2024-10-01T05:18:55Z")

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Thanks it was sorted out!