This is used to specify a shielded Born-Meyer potential binary ionic clusters with
anions and cations having the same magnitude charge.
The atoms must be in the order cation, anion, cation, anion, etc. The energy is:
The parameters that can
be specified with PARAMS are , the magnitude of the ionic charges, a single
value of , assumed to be the same for all interactions, and , and
, in order. Default values for KCl are set for all parameters except .
Atomic units are assumed. Subroutines used: ions.