[lammps-users] Thermal temperature

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1

Hello,

what I want to know is, in Lammps, when calculating temperature, is the global translational motion (i.e. center-of-mass velocity) component removed already? I assume it to be yes as computer_modify command specifies extra = 3 by default--if I understand correctly. But why if I give all the atoms an additional group velocity on, let's say, direction z, the temperature is increased significantly (which is not expected to occur)?

If global translational motion is taken into account in default setup, which command serves to remove it? I looked much into temp/***** in compute command group, but cannot get any ideas how to do it ...

Thanks and with best regards!

Xiang Gu

2

No, the center of mass V is not subtracted off. You probably
don't want to include atoms with a big z velocity in the T computation
(don't put them in the group), or exclude z altogether via
compute temp/partial.

Steve