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$MOROKM group (relevant if RUNTYP=EDA)
This performs an analysis of the energy contributions
to dimerization (or formation of larger clusters of up to
ten monomers), according to the Morokuma-Kitaura and/or
Reduced Variational Space schemes. The analysis is limited
to closed shell RHF monomers. In other words, the monomers
should be distinct molecular species: avoid breaking
chemical bonds! For more general energy decompositions,
see the $LMOEDA input group. See also PIEDA in the FMO
codes.
Solvation models are not supported.
MOROKM = a flag to request Morokuma-Kitaura decomposition.
(default is .TRUE.)
RVS = a flag to request "reduced variation space"
decomposition. This differs from the Morokuma
analysis. One or the other or both may be
requested in the same run. (default is .FALSE.)
Generally speaking, RVS handles non-orthogonality of
monomers better. When diffuse functions are used, the
MOROKM analysis sometimes fails, but RVS will work.
BSSE = a flag to request basis set superposition error
be computed. You must ensure that CTPSPL is
selected. This option applies only to MOROKM
decompositions, as a basis superposition error is
automatically generated by the RVS scheme. This
is not the full Boys counterpoise correction, as
explained in the reference. (default is .FALSE.)
* * *
The inputs here control how the RHF supermolecule, whose
coordinates are given in the $DATA input group, is divided
into two or more monomers.
IATM = An array giving the number of atoms in each of
the monomer. Up to ten monomers may be defined.
Your input in $DATA must have all the atoms in
the first monomer defined before the atoms in the
second monomer, before the third monomer... The
number of atoms belonging to the final monomer
can be omitted. There is no sensible default for
IATM, so don't omit it from your input.
ICHM = An array giving the charges of the each monomer.
The charge of the final monomer may be omitted,
as it is fixed by ICH in $CONTRL, which is the
total charge of the supermolecule. The default
is neutral monomers, ICHM(1)=0,0,0,...
EQUM = an array to indicate all monomers are equivalent
by symmetry (in addition to containing identical
atoms). If so, which is not often true, then only
the unique computations will be done.
(default is .FALSE.,.FALSE., ...)
* * *
CTPSPL = a flag to decompose the interaction energy into
charge transfer plus polarization terms. This
is most appropriate for weakly interacting
monomers. (default is .TRUE.)
CTPLX = a flag to combine the CT and POL terms into a
single term. If you select this, you might want
to turn CTPSPL off to avoid the extra work that
that decomposition entails, or you can analyze
both ways in the same run. (default is .FALSE.)
RDENG = a flag to enable restarting, by reading the
lines containing "FINAL ENERGY" from a previous
run. The $EMORO group is single lines read under
format A16,F20.10 containing the energies, and a
card $END to complete. The 16 chars = anything.
(default is .FALSE.)
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The present implementation has some quirks:
1. The initial guess of the monomer orbitals is not
controlled by $GUESS. The program first looks for a $VEC1,
$VEC2, ... group for each monomer. The orbitals must be
obtained for the identical coordinates which that monomer
has within the supermolecule. If any $VECn groups are
found, they will be MOREAD. If any are missing, the guess
for that monomer will be constructed by HCORE. Check your
monomer energies carefully! The initial guess orbitals for
the supermolecule are formed from a block diagonal matrix
containing the monomer orbitals.
2. The use of symmetry is turned off internally.
3. Spherical harmonics (ISPHER=1) may not be used.
4. There is no direct SCF option. File ORDINT will be a
full C1 list of integrals. File AOINTS will contain
whatever subset of these is needed for each particular
decomposition step. So extra disk space is needed compared
to RUNTYP=ENERGY.
5. This run type applies only to ab initio RHF treatment of
the monomers. To be quite specific: this means that DFT
(which involves a grid, not just integrals) will not work,
nor will MOPAC's approximated 2e- integrals
6. This kind of calculation will run in parallel.
Quirks 1, 3 and 4 can be eliminated by using PIEDA if only
two monomers are present. For more monomers PIEDA results
will slightly differ. PIEDA is a special case of FMO, q.v.
References:
C.Coulson in "Hydrogen Bonding", D.Hadzi, H.W.Thompson,
Eds., Pergamon Press, NY, 1957, pp 339-360.
C.Coulson Research, 10, 149-159 (1957).
K.Morokuma J.Chem.Phys. 55, 1236-44 (1971).
K.Kitaura, K.Morokuma Int.J.Quantum Chem. 10, 325 (1976).
K.Morokuma, K.Kitaura in "Chemical Applications of
Electrostatic Potentials", P.Politzer,D.G.Truhlar, Eds.
Plenum Press, NY, 1981, pp 215-242.
The method coded is the newer version described in the 1976
and 1981 papers. In particular, note that the CT term is
computed separately for each monomer, as described in the
words below eqn. 16 of the 1981 paper, not simultaneously.
Reduced Variational Space:
W.J.Stevens, W.H.Fink, Chem.Phys.Lett. 139, 15-22(1987).
A comparison of the RVS and Morokuma decompositions can be
found in the review article: "Wavefunctions and Chemical
Bonding" M.S.Gordon, J.H.Jensen in "Encyclopedia of
Computational Chemistry", volume 5, P.V.R.Schleyer, editor,
John Wiley and Sons, Chichester, 1998.
BSSE during Morokuma decomposition:
R.Cammi, R.Bonaccorsi, J.Tomasi
Theoret.Chim.Acta 68, 271-283(1985).
The present implementation:
"Energy decomposition analysis for many-body interactions,
and application to water complexes"
W.Chen, M.S.Gordon J.Phys.Chem. 100, 14316-14328(1996)
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