$EFRAG
$EFRAG group (optional)
This group gives the name and position of one or more
effective fragment potentials. It consists of a series of
free format card images, which may not be combined onto a
single line! The position of a fragment is defined by
giving any three points within the fragment, relative to
the ab initio system defined in $DATA, since the effective
fragments have a frozen internal geometry. All other
atoms within the fragment are defined by information in
the $FRAGNAME group.
-1- a line containing one or more of these options:
- COORD
- =CART selects use of Cartesians coords
to define the fragment position at
line -3-. (default)
- =INT selects use of Z-matrix internal
coordinates at line -3-.
- POLMETHD
- =SCF indicates the induced dipole for
each fragment due to the ab initio
electric field and other fragment
fields is updated only once during
each SCF iteration.
- =FRGSCF requests microiterations during
each SCF iteration to make induced
dipoles due to ab initio and other
fragment fields self consistent
amoung the fragments. (default)
Both methods converge to the same
dipolar interaction.
- POSITION
- =OPTIMIZE Allows full optimization within the
ab initio part, and optimization of
the rotational and translational
motions of each fragment. (default)
- =FIXED Allows full optimization of the
ab initio system, but freezes the
position of the fragments. This
makes sense only with two or more
fragments, as what is frozen is the
fragments' relative orientation.
- =EFOPT the same as OPTIMIZE, but if the
fragment gradient is large, up to
5 geometry steps in which only the
fragments move may occur, before
the geometry of the ab initio piece
is relaxed. This may save time by
reusing the two electron integrals
for the ab initio system.
Input a blank line if all the defaults are acceptable.
-2- FRAGNAME=XXX,
XXX is the name of the fragment whose coordinates are to
be given next. All other information defining the
fragment is given in a supplemental $XXX group, which is
referred to below as a $FRAGNAME group.
A RHF/DZP EFP for water is internally stored in GAMESS.
Choose FRAGNAME=H2OEF2 to look up this numerical data,
and then skip the input of $H2OEF2 and $FRGRPL groups.
-3- NAME, X, Y, Z (COORD=CART)
NAME, I, DISTANCE, J, BEND, K, TORSION (COORD=INT)
- NAME
- = the name of a fragment point. The name used
here must match one of the points in $FRAGNAME.
- X, Y, Z
- = Cartesian coordinates defining the position of
this fragment point RELATIVE TO THE COORDINATE
ORIGIN used in $DATA. The choice of units is
controlled by UNITS in $CONTRL.
- I, DISTANCE, J, BEND, K, TORSION
- = the usual Z-matrix
connectivity internal coordinate definition.
The atoms I, J, K must be atoms in the ab
initio system from in $DATA, or fragment points
already defined in the current fragment or
previously defined fragments.
Line -3- must be given a total of three times to define
this fragment's position.
Repeat lines -2- and -3- to enter as many fragments as you
desire, and then end the group with a $END line.
Note that it is quite typical to repeat the same fragment
name at line -2-, to use the same fragment system at many
different positions.
For tips on effective fragment potentials
see the 'further information' section
Back to list of input groups...