 geometric region of atoms 
    <LI>
    remainder = rest of uninitialized atoms 
</UL>
<PRE>
coeffs:  types
               (1) lowest atom type
               (2) highest atom type
         molecules
               (1) lowest molecule ID
               (2) highest molecule ID
         region
               (1) lower x bound of region
               (2) upper x bound of region
               (3) lower y bound of region
               (4) upper y bound of region
               (5) lower z bound of region
   