$STONE group      (optional)
 
    This group defines the expansion points for Stone's
distributed multipole analysis (DMA) of the electrostatic
potential.
 
    The DMA takes the multipolar expansion of each overlap
charge density defined by two Gaussian primitives, and
translates it from the center of charge of the overlap
density to the nearest expansion point.  Some references
for the method are
 
    A.J.Stone  Chem.Phys.Lett.  83, 233-239 (1981)
    A.J.Stone, M.Alderton  Mol.Phys.  56, 1047-1064(1985)
    A.J.Stone  J.Chem.Theory and Comput. 1, 1128-1132(2005)
 
    The existence of $STONE input is what triggers the
analysis. The first set of lines must appear as the first
line after $STONE (enter a blank line if you make no
choice), then enter as many choices as you wish, in any
order, from the other sets.
 
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BIGEXP    exponents larger than this are treated by
                 the original Stone expansion, and those
                 smaller by a numerical integration.  The
                 default is 0.0, meaning no numerical grid.
                 The other parameters are meaningless if
                 BIGEXP remains zero.
 
NRAD       number of radial grid points (default 100)
NANG       number of angular grid points, choose one
                 of the Lebedev grid values (default 590)
SMOOTH   degree of Becke smoothing (default=2)
SMRAD    Radii choice, 0=constant, 1=Bragg-Slater,
                 which is the default.
 
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ATOM i name, where
 
      ATOM     is a keyword indicating that a particular
               atom is selected as an expansion center.
      i        is the number of the atom
      name     is an optional name for the atom. If not
               entered the name will be set to the name
               used in the $DATA input.
 
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ATOMS          is a keyword selecting all nuclei in the
               molecule as expansion points.  No other
               input on the line is necessary.
 
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BONDS          is a keyword selecting all bond midpoints
               in the molecule as expansion points.  No
               other input on the line is necessary.
 
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BOND i j name, where
 
      BOND     is a keyword indicating that a bond mid-
               point is selected as an expansion center.
      i,j      are the indices of the atoms defining the
               bond, corresponding to two atoms in $DATA.
      name     an optional name for the bond midpoint.
               If omitted, it is set to 'BOND'.
 
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CMASS          is a keyword selecting the center of mass
               as an expansion point.  No other input on
               the line is necessary.
 
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POINT x y z name, where
 
      POINT    is a keyword indicating that an arbitrary
               point is selected as an expansion point.
      x,y,z    are the coordinates of the point, in Bohr.
      name     is an optional name for the expansion
               point.  If omitted, it is set to 'POINT'.
 
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While making the EFPs for QM/MM run, a single keyword
QMMMBUF is necessary.  Adding additional keywords may lead
to meaningless results.  The program will automatically
select atoms and bond midpoints which are outside the
buffer zone as the multipole expansion points.
 
QMMMBUF  nmo, where
 
      QMMMBUF  is a keyword specifying the number of QM/MM
               buffer molecular orbitals, which must be the
               first NMO orbitals in the MO set.  These
               orbitals must be frozen in the buffer zone,
               so this is useful only if $MOFRZ is given.
      NMO      is the number of buffer MO-s
               (if NMO is omitted, it will be set to the
               number of frozen MOs in $MOFRZ)
 
The second and third moments on the printout can be
converted to Buckingham's tensors by formula 9 of
  A.D.Buckingham, Quart.Rev. 13, 183-214 (1959)
These can in turn be converted to spherical tensors
by the formulae in the appendix of
  S.L.Price, et al.  Mol.Phys. 52, 987-1001 (1984)