text: 3 
  
  2 
  
  1 
  
  0 
  
  (b) 
  3 
  
  2 
  
  1 
  
  0 
  
  4  8  6  10 
  r (Å) 
  
  FIG. 3: Eﬀective pair potentials derived for MSA3 and 
  BIMSA3. (a) Cation anion (dashed line: without taking the 
  pair into account), (b) pair cation, (c) pair anion, and (d) pair 
  pair. The internal potential of the pair β eVint(r) is set equal 
  to βV eﬀ  ij (r) for distances less than 4 ˚A. 