 read in from a data or restart file
for lj/cutoff, lj/shift, class2/cutoff styles, 
  offset flag only affects printout of thermodynamic energy
  (not forces or dynamics), determines whether offset energy 
  is added in to LJ potential to make value at cutoff = 0.0,
  flag = 0 -&gt; do not add in offset energy,
  flag = 1 -&gt; add in offset energy 
for lj/smooth and lj/charmm styles, outer cutoff must be &gt; inner cutoff
for lj/smooth and lj/charmm styles, atom pairs less than the inner cutoff
  distance