or 1-4 interactions (distance units)

define (or override) nonbond coefficients for an individual atom type pair
use appropriate number of coeffs for a particular style
1st atom type must be <= 2nd atom type
all cutoffs are in global units, not local sigma units
  (e.g. in reduced units a setting of "lj/cutoff 1.0 1.2 2.5" means a 
  cutoff of 2.5, not 1.2*2.5)
turn off a particular type pair interaction by setting the
  cutoff to 0.0 (both cutoffs to zero for lj/smooth option)
for soft style, prefactor A i