e 
    <LI>
    energy = epsilons 
    <LI>
    velocity = sigmas/tau 
    <LI>
    force = reduced LJ force (sigmas/tau^2) 
</UL>
<PRE>
for LJ units, LAMMPS sets global epsilon,sigma,mass all equal to 1.0
subsequent input numbers in data and command file must be in these units
output numbers to screen and log and dump files will be in these units
this command (if it appears) must be the first command (aside from
  comments) in the input script
must be set before data or restart file is read

Default = real