dt = timestep size (time units)
timestep 2.0 timestep 0.003
Set the timestep size for subsequent molecular dynamics simulations. See the units command for the time units associated with each choice of units that LAMMPS supports.
The default value for the timestep size also depends on the choice of units for the simulation; see the default values below.
When the run style is respa, dt is the timestep for the outer loop (largest) timestep.