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Bug #1354

Constant acceleration NEMD is broken.

Added by David van der Spoel about 6 years ago. Updated 11 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 about 6 years ago

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

#2 Updated by Mark Abraham about 6 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 about 6 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 about 6 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 almost 6 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 almost 6 years ago

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

#7 Updated by Erik Lindahl over 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 over 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 over 3 years ago

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

#10 Updated by Mark Abraham over 3 years ago

  • Target version deleted (5.x)

#11 Updated by Mark Abraham 11 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 11 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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