neighbors 
</UL>
<PRE>
weighting factors to turn on/off nonbond interactions of atom pairs that
  are &quot;close&quot; in the molecular topology
1-2 neighbors are a pair of atoms connected by a bond
1-3 neighbors are a pair of atoms 2 hops away, etc.
weight values are from 0.0 to 1.0 and are used to multiply the
  energy and force interaction (both Coulombic and LJ) between the 2 atoms
weight of 0.0 means no interaction
weight of 1.0 means full interaction
can either specify a single keyword (charmm, amber