$DISREP group                               (optional)
 
   This group controls evaluation of the dispersion and
repulsion energies by the empirical method of Floris and
Tomasi.  The group must be given when IDISP=1 in $PCM,
whenever the solvent is not water.  Only one of the two
options ICLAV or ILJ should be selected.  Due to its lack
of parameters, almost no one chooses ILJ.
 
ICLAV = selects Claverie's disp-rep formalism.
      = 0 skip computation.
      = 1 Compute the solute-solvent disp-rep interaction
          as a sum over atom-atom interactions through a
          Buckingham-type formula (R^-6 for dispersion,
          exp for repulsion).  (default)
          Ref: Pertsin-Kitaigorodsky "The atom-atom
               potential method", page 146.
 
ILJ   = selects a Lennard-Jones formalism.
      = 0 skip computation. (default)
      = 1 solute atom's-solvent molecule interaction is
          modeled by Lennard-Jones type potentials, R^-6
          for dispersion, R^-12 for repulsion).
 
---- the following data must given for ICLAV=1:
 
RHO   = solvent numeral density
N     = number of atom types in the solvent molecule
NT    = an array of the number of atoms of each type in a
        solvent molecule
RDIFF = distances between the first atoms of each type
        and the cavity
DKT   = array of parameters of the dis-rep potential for
        the solvent
RWT   = array of atomic radii for the solvent
 
The defaults are appropriate for water,
   RHO=3.348D-02
   N=2
   NT(1)=2,1
   RDIFF(1)=1.20,1.50
   DKT(1)=1.0,1.36
   RWT(1)=1.2,1.5
 
DKA   = array of parameters of the dis-rep potential for
        the solute.  Defaults are provided for some common
        elements:
        H: 1.00   Be: 1.00   B: 1.00   C: 1.00
        N: 1.10    O: 1.36   P: 2.10   S: 1.40
 
RWA   = array of atomic radii for the solute to compute
        dis-rep.  Defaults are provided for some common
        elements:
        H: 1.20   Be: 1.72   B: 1.72   C: 1.72
        N: 1.60    O: 1.50   P: 1.85   S: 1.80
 
Other elements have DKA and RWA values of 0.0 and so must
be  given in the input deck, or the dispersion/repulsion
energy will be 0.  For EFP/PCM calculations, only QM atoms
need DKA and RWA values to calculate the DIS-REP energy.
 
---- the following data must given for ILJ=1:
 
RHO   = solvent numeral density
EPSI  = an array of energy constants referred to each atom
        of the solute molecule.
SIGMA = an array of typical distances, relative to each
        solute atom