[gmx-developers] Large VCM(group rest): Temp-cm: inf

[Carsten Kutzner]

Hi,

we appear to have another small problem with the CVS version.
For a protein in water system, where comm-grps=Protein is
chosen we continuously get the following line outputted to log:

Large VCM(group rest):      0.00005,     -0.00002,     -0.00004, Temp-cm:          inf
Large VCM(group rest):      0.00006,     -0.00003,     -0.00004, Temp-cm:          inf
Large VCM(group rest):      0.00006,     -0.00003,     -0.00003, Temp-cm:          inf
Large VCM(group rest):      0.00006,     -0.00004,     -0.00002, Temp-cm:          inf
Large VCM(group rest):      0.00006,     -0.00005,     -0.00001, Temp-cm:          inf
...

This happens also for the non-MPI mdrun. The problem is that in check_cm_grp (vcm.c)
the number of degrees of freedom for the 2nd group are zero. Thus

Temp_cm = 2*ekcm/vcm->group_ndf[g];

becomes infinity, triggering the message. This is just an output problem, since
nothing needs to be done to the COM of the second group anyway. However, the md.log files
become HUGE when this is outputted at every step.

Carsten




-- 
Dr. Carsten Kutzner
Max Planck Institute for Biophysical Chemistry
Theoretical and Computational Biophysics Department
Am Fassberg 11
37077 Goettingen, Germany
Tel. +49-551-2012313, Fax: +49-551-2012302
www.mpibpc.mpg.de/home/grubmueller/
www.mpibpc.mpg.de/home/grubmueller/ihp/ckutzne/