$CIMFRG group
                  (required when CIMTYP=GSECIM in $CONTRL;
  relevant to single- and multi-level GSECIM calculations)
 
    In free-format, provide an array of the comma or dash
separated integers labeling the atoms. Integers in each
row, which must be listed in parentheses, represent the
user-specified group of atoms that are used to identify
central occupied LMOs in the initial steps of the GSECIM
subsystem design. When generating subsystems, the atoms
specified in a given row will always be kept together.
Optionally, one can provide the name of the method to be
applied to the group of atoms listed in a given row. The
hydrogen atoms do not have to be included, since each
hydrogen atom is assigned to the nearest non-hydrogen atom,
although there may be cases where listing hydrogens is
useful if there is ambiguity in assigning hydrogens to non-
hydrogen atoms. The subsystems involving atoms that are not
represented in $CIMFRG will be determined using the
standard SECIM algorithm and treated with the method
defined by SUBMTD in $CIMINP. For example,
 
 $CIMFRG
 1 (3-4,6) CR-CCL
 2 (1-2,11) CCSD
 3 (14,34,50)
 4 (16,18,54)
 5 (21-22,26,30)
 6 (37-38,42,46)
 $END
 
implies that atoms 3, 4, and 6 (and adjacent hydrogens, if
any) will be used to identify central LMOs that define the
1st subsystem in the initial steps of the GSECIM algorithm,
which will be treated by CR-CC(2,3). Similarly, atoms 1, 2,
and 11 (and adjacent hydrogens, if any) will be used to
identify central LMOs that define the 2nd subsystem in the
initial steps of the GSECIM algorithm, which will be
treated by CCSD, whereas atoms 14, 34, and 50 (and adjacent
hydrogens, if any) will be used to identify central LMOs
that define the 3rd subsystem in the initial steps of the
GSECIM algorithm which will be treated by the method
defined by SUBMTD in $CIMINP, etc. The remaining atoms will
be treated by the standard SECIM algorithm and the method
defined by SUBMTD in $CIMINP.
 
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