[gmx-users] angular momentum.

[Nguyen Hoang Phuong]

> > 
> >>Dear All,
> >>
> >>the simulations of a peptide in vacuum are performed using NVE
> >>ensemble. In principal, the angular momentum of the molecule should be
> >>conserved but in my simulations, its magnitude  increases as a function of
> >>time. Does anyone know why?
> > 
> > 
> > Yes, it is caused by a build-up of integration and/or round-off
> > errors, which unfortunately is inevitable in a computersimulation.
> > Try David's suggestion...
> > 
> 
> Actually, it's probably due to your neighborlist not being longer than 
> the cutoff; I'm adding some code to improve this for 3.1.5 (or 3.2, we
> might have changed enough things to bump the release).

the simulations run with: 
rlist = 1.
rcoulonb =1.
rvdw = 1.
PME was used.
I wonder if these values cause the problem? After 10ps, the magnitude of
the angular momentum is increased by a factor of 5, the timestep is
0.5fs and double precision is switched on. Within this short
simulation time, does the numerical error of intergrations is big enough?

Thanks for your help.

Phuong
------
> 
> Cheers,
> 
> Erik
> 
> 
> 
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