Internal degrees of freedom

Hi all, I am interested in simulate a metallic NP, but take into account only the internal degrees of freedom. It is excluding the traslational and rotational contributions. Is there a command to reset the angular and lineal momentum at every step of the simulation?. I will be appreciate it if anyone can give me a suggestion. Thank in advance

Hi all, I am interested in simulate a metallic NP, but take into account
only the internal degrees of freedom. It is excluding the traslational and
rotational contributions. Is there a command to reset the angular and lineal
momentum at every step of the simulation?. I will be appreciate it if anyone
can give me a suggestion. Thank in advance

have you looked at fix momentum?
it is probably too obvious.

http://lammps.sandia.gov/doc/fix_momentum.html

BTW: i don't think it is a good idea to reset the global
angular and linear momentum at every step. due to using
a finite step integration, there are fluctuations that should
occur and not suppressed. all you need to do is avoid
buildup of a drift.

axel.

Dear Axel Kohlmeyer, really did not see the fix. That is just what I needed.
With regard to your comment. The vibrational spectra are modified if contemplate the rotation and translation, is why that should be excluded from the simulations directly. However, not at every step.
Thank you very much for your help!!!
Oscar

2011/12/22 Axel Kohlmeyer <[email protected]>