Feature #1026

request for gen_vel to work with multiple temperature coupling groups at different temperatures

Added by Chris Neale about 8 years ago. Updated about 4 years ago.

Target version:


The output of grompp from v4.5.5 suggests that gen_vel only uses the first value given, although there is no error if multiple temperatures are listed. i.e. if I supply two temperatures to gen_vel, then I only get one message "Velocitied were taken from a Maxwell distribution at X K, where X is the first listed temperature.

Perhaps this is just an output issue with grompp. I was using the sd integrator.

Related issues

Related to GROMACS - Bug #1893: grompp fails to warn about .mdp values with the wrong typeClosed


#1 Updated by Roland Schulz about 8 years ago

I think this is a more general problem. Grompp accepts also multiple values for other variables (e.g. tinit or nsteps) and ignores them.

#2 Updated by Teemu Murtola about 8 years ago

Is this a bug report about grompp silently accepting and ignoring some extra invalid input values (as the description suggests), or a request for it to actually do something with those values (like the title and the type suggest)?

If it is a bug report, then 5.0 could be the proper target version (and the type and title should be fixed). If we move to use the C++ options mechanism for parsing mdp options, this would likely get fixed more or less automatically.

#3 Updated by Chris Neale about 8 years ago

This post was intended as an enhancement request. I did note a bug here, and that bug should probably be fixed, but I am not sure how useful it is to allow multiple temperature coupling groups and not allow multiple temperatures for velocity generation, so simply noting that the extra values are not used doesn't solve much beyond ensuring that the user knows what they are getting.

Please feel free to modify this into a bug or feature request as you see fit.

#4 Updated by Mark Abraham about 4 years ago

  • Related to Bug #1893: grompp fails to warn about .mdp values with the wrong type added

#5 Updated by Mark Abraham about 4 years ago

The fix for #1893 inadvertently made grompp complain when an mdp field had too many groups (as many users used to do for pressure coupling, which does not support groups).

The gen_vel feature is still not implemented.

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