[gmx-developers] Define an new group

[Erik Lindahl]

Hi Rebecca,

I have to confess it was a _long_ time since I looked into these parts of
the code, but you might be able to achieve this simply by defining a group,
giving it the initial velocity you want, and then using the
constant-acceleration functionality with the value 0.0 (since zero constant
acceleration means constant speed).

And if that fails, it should be possible to fix it without too much effort
:-)

Otherwise, the idea of the user groups is exactly that you should be able
to quickly implement a small routine where you do something to an arbitrary
group without having to redefine the input mdp options, create a new
(incompatible) TPR version, and also having to modify the enum lists.

Cheers,

Erik

On Fri, Apr 10, 2020 at 12:55 PM Rebecca Kleemann <
rkleeman at students.uni-mainz.de> wrote:

> Hi,
>
> I want to add a group to set atoms to a constant velocity.
>
> enum
> {
>     egcTC,    egcENER,   egcACC, egcFREEZE,
>     egcUser1, egcUser2,  egcVCM, egcCompressedX,
>     egcORFIT, egcQMMM,
>     egcNR
> };
>
> const char *gtypes[egcNR+1] = {
>     "T-Coupling", "Energy Mon.", "Acceleration", "Freeze",
>     "User1", "User2", "VCM", "Compressed X", "Or. Res. Fit", "QMMM",
> nullptr
> };
>
> Are "User1" and "User2" meant to be used like that and can they be renamed
> or should I add a new group and increase the number of groups?
>
> Greetings,
>
> Rebecca
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-- 
Erik Lindahl <erik.lindahl at dbb.su.se>
Professor of Biophysics, Dept. Biochemistry & Biophysics, Stockholm
University
Science for Life Laboratory, Box 1031, 17121 Solna, Sweden
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