timestep 2.0 timestep 0.003
Set the timestep size for subsequent molecular dynamics simulations. See the units command for a discussion of time units. The default value for the timestep 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.
fix dt/reset, run, run_style respa, units
Default:timestep = 0.005 tau for units = lj