Re: [ESPResSo-users] Saving old velocity

[Axel Arnold]

Hi!

On 06/20/2014 04:38 PM, Mohammad Abdulkhaliq wrote:
> I want to save the particle's old velocity at the previous time step.
> So, I want to make sure if this the correct way ? 
>
> I included v_old in ParticleMomentum struct in particle data and added
> corresponding methods 
>
> set_particle_v_old
> mpi_send_v_old
> mpi_send_v_old_slave

ParticleMomentum contains the _current_ momentum information and for
certain algorithms is communicated to other nodes, which you don't need.
So you should store your old velocity better in the ParticleLocal
struct, which contains nonstatic information about the particle that
only the node holding the particle needs to know.

Also, you don't need to write the set_particle_v_old and mpi_send_v_*
functions. These serve to set the particle property from the Tcl level,
but you actually want to update that information in the integrator loop,
which is in C (integrate.cpp). You can just copy the current velocity in
the *_update_vel_* function.

Best,
Axel

-- 
JP Dr. Axel Arnold
ICP, Universität Stuttgart
Allmandring 3
70569 Stuttgart, Germany
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Tel: +49 711 685 67609