set velocity and fact velocity

Hi there

i need to set initial velocity of box
velocity box set NULL -8 NULL

but from simulation obtain -28.92 at zero time. What wrong?

What does "box" mean? Do you mean
a group of atoms that you are calling the "box"?

If so, the difference between 8 and 28.92 could
be box vs lattice units. See the "units" option
of the velocity command.