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Bug #1354

Constant acceleration NEMD is broken.

Added by David van der Spoel over 5 years ago. Updated 3 months ago.

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

Constant acceleration NEMD has probably been broken for over four years since a6ee084bcf removed the only call to update_ekindata().


Related issues

Related to GROMACS - Task #1971: Removing buggy features vs. keeping workflows New

History

#1 Updated by Mark Abraham over 5 years ago

Also does not get anything checkpointed, but not sure that is relevant.

#2 Updated by Mark Abraham over 5 years ago

Also, it gets turned on by

(opts->ngacc > 1 || norm(opts->acc[0]) > 0)
i.e. that there is more than one acceleration group or that the first acceleration group has a non-zero acceleration. This does not deal with the silly case of multiple zero-norm acceleration groups.

#3 Updated by Michael Shirts over 5 years ago

Can you be more specific about what is broken? We're actually trying to use it to compute contact angles. The drop is indeed accelerating until it hits a terminal velocity --- but now I'm not sure how to interpret that!

#4 Updated by David van der Spoel over 5 years ago

Haven't looked into it yet, but I opened this redmine in order not to forget about it.

#5 Updated by Mark Abraham over 5 years ago

Michael Shirts wrote:

Can you be more specific about what is broken? We're actually trying to use it to compute contact angles. The drop is indeed accelerating until it hits a terminal velocity --- but now I'm not sure how to interpret that!

e.g. search git show a6ee084bcf3ac87d9dd493702b1c737d86506bdc for update_ekindata. That function used to be called from update(...) to compute some kind of group-based KE things. Now that function is never called, so who knows what junk is being computed!

#6 Updated by Rossen Apostolov about 5 years ago

Michael: do you have a working version or shall we remove the funcionality completely?

#7 Updated by Erik Lindahl almost 5 years ago

David/Michael - unless somebody volunteers to look into it, we'll remove the feature before 5.0.

#8 Updated by Berk Hess almost 4 years ago

It shouldn't be hard to fix this, but if nobody uses it, it's better to remove it.
We shouldn't forget to also remove ekind->grpstat[g].u.

#9 Updated by Mark Abraham almost 3 years ago

  • Related to Task #1971: Removing buggy features vs. keeping workflows added

#10 Updated by Mark Abraham almost 3 years ago

  • Target version deleted (5.x)

#11 Updated by Mark Abraham 3 months ago

I'll remove this. Ten years is long enough for something to sit broken and unfixed. Simplifying the update code would be very useful right now.

#12 Updated by Gerrit Code Review Bot 3 months ago

Gerrit received a related patchset '1' for Issue #1354.
Uploader: Mark Abraham ()
Change-Id: gromacs~master~I3d8b3c89ec0a65655aca30a35a722f4010a9f782
Gerrit URL: https://gerrit.gromacs.org/8944

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