Example: FDE: H2O in water

Download FDE_H2O_128.run

This example demonstrates how to use FDE in combination with a large environment, that is modeled as a superposition of the densities of isolated molecules. Here, the excitation energies of a water molecule surrounded by an environment of 127 water molecules. For details, see also: C.R. Jacob, J. Neugebauer, L. Jensen and L. Visscher, Comparison of frozen-density embedding and discrete reaction field solvent models for molecular properties, Physical Chemistry Chemical Physics 8, 2349 (2006)

This calculation consists of two steps:

  • First a prototype water molecule is calculated.
  • Next the embedding calculation of water in water is performed.

To reduce the amount of output the next lines are included in the adf calculations:

EPRINT
  SFO NOEIG NOOVL NOORBPOP
  SCF NOPOP
END
NOPRINT BAS FUNCTIONS

First, a prototype water molecule is calculated. The density of this isolated water molecules will afterwards be used to model the environment.

$ADFBIN/adf << eor
Title Input generated by modco

UNITS
  length bohr
  angle degree
END

XC
LDA
END

SYMMETRY NOSYM

GEOMETRY
  sp
END

SCF
  iterations 50
  converge 1.0e-6 1.0e-6
  mixing 0.2
  lshift 0.0
  diis n=10 ok=0.5 cyc=5 cx=5.0 cxx=10.0
END
NumericalQuality good

FRAGMENTS
  O  t21.DZP.O
  H  t21.DZP.H
END

ATOMS
 O       -11.38048700000000    -11.81055300000000     -4.51522600000000
 H       -13.10476265095705    -11.83766918322447     -3.96954531282721
 H       -10.51089289290947    -12.85330720999229     -3.32020577897331
END

ENDINPUT
eor

mv TAPE21 t21.mol_1

Afterwards, the FDE calculation is performed. In this FDE calculation, there is one nonfrozen water molecule and the previously prepared water molecule is included as a frozen fragment that is duplicated 127 times. For this frozen fragment, the more efficient fitted density is used.

...

$ADFBIN/adf << eor
Title Input generated by modco

UNITS
  length bohr
  angle degree
END

XC
MODEL SAOP
END

SYMMETRY NOSYM

SCF
  iterations 50
  converge 1.0e-6 1.0e-6
  mixing 0.2
  lshift 0.0
  diis n=10 ok=0.5 cyc=5 cx=5.0 cxx=10.0
END

EXCITATION
  ONLYSING
  LOWEST  5
END

NumericalQuality good

FRAGMENTS
  O      t21.DZP.O
  H      t21.DZP.H
  frag1  t21.mol_1 type=fde &
    fdedenstype SCFfitted
  SubEnd
END

ATOMS
 O   0.00000000000000   0.00000000000000   0.00000000000000
 H  -1.43014300000000   0.00000000000000   1.10739300000000
 H   1.43014300000000   0.00000000000000   1.10739300000000
 O -11.38048700000000 -11.81055300000000  -4.51522600000000  f=frag1/1
 H -13.10476265095705 -11.83766918322447  -3.96954531282721  f=frag1/1
 H -10.51089289290947 -12.85330720999229  -3.32020577897331  f=frag1/1
 O  -1.11635000000000   9.11918600000000  -3.23094800000000  f=frag1/2
 H  -2.82271357869859   9.71703285239153  -3.18063201242303  f=frag1/2
 H  -0.12378551814273  10.53819303003839  -2.70860866559857  f=frag1/2
 O   5.96480100000000   4.51370300000000   3.70332800000000  f=frag1/127
 H   5.24291272273548   3.06620845434369   2.89384293177905  f=frag1/127
 H   4.73614594944492   5.00201400735317   4.93765482424434  f=frag1/127
END

FDE
  PW91K
END

ENDINPUT
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