input - they are
  always mixed geometrically, regardless of mixing style setting
for nonbond style "lj/charmm", mixing style is always arithmetic,
  regardless of mixing style setting
must be set before data file is read

Default = geometric for all nonbond styles except
          arithmetic for nonbond style lj/charmm
          sixthpower for nonbond style class2/cutoff
</PRE>
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<H3>
<A NAME="_cch3_931276654">neighbor </A></H3>
<UL>
    <LI>
    1st parameter = skin distance in distance units 
    <LI>