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Bug #2201

Constraint COM pull forces incorrect with SD integrator

Added by Berk Hess over 2 years ago. Updated about 2 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Category:
mdrun
Target version:
Affected version - extra info:
Affected version:
Difficulty:
uncategorized
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Description

With the SD integrator, the reported constraint pull forces are only for the SD random update, so fully basically Gaussian distributed. This can not have caused unnoticed errors.

Associated revisions

Revision 41fa5855 (diff)
Added by Berk Hess over 2 years ago

Fix COM pull force with SD

The reported COM pull force when using the SD integrator was random
only. Now the pull force is summed over the systematic and random
SD update components.
A better solution is to not add the random force at all, but such
a change should not be done in a release branch.

Fixes #2201.

Change-Id: I10a56b30b952869396d170914bcbc0163299a1c8

History

#1 Updated by Gerrit Code Review Bot over 2 years ago

Gerrit received a related patchset '1' for Issue #2201.
Uploader: Berk Hess ()
Change-Id: gromacs~release-2016~I10a56b30b952869396d170914bcbc0163299a1c8
Gerrit URL: https://gerrit.gromacs.org/6693

#2 Updated by Berk Hess over 2 years ago

  • Status changed from In Progress to Fix uploaded

I pushed up a fix to v2016 that sums the systematic and random constraint forces. Magnus, could you test this?
A better solution is to not add the random pull force. I'm working on that for master.

#3 Updated by Berk Hess over 2 years ago

  • Status changed from Fix uploaded to Resolved

#4 Updated by Mark Abraham over 2 years ago

  • Status changed from Resolved to In Progress
  • Target version changed from 2016.4 to 2018

Updating status to reflect Berk's intent to do something that might make it into 2017.

#5 Updated by Berk Hess over 2 years ago

  • Status changed from In Progress to Resolved

A fix has been merged into release-2016. With this fix the friction and random forces are still included in the pull force, but those are many orders of magnitude smaller than the systematic forces, so this is not an issue.

#6 Updated by Mark Abraham over 2 years ago

  • Target version changed from 2018 to 2016.4

#7 Updated by Mark Abraham about 2 years ago

  • Status changed from Resolved to Closed

#8 Updated by Marvin Bernhardt about 2 years ago

This seems to also effect simulations with the v-rescale thermostat and low tau-t values.

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