Example: NOCV: CH3 – CH3¶

#! /bin/sh


# Example for calculation of ETS-NOCV for simulated unrestricted fragments. ETS-NOCV:
# energy analysis using the Natural Orbitals for Chemical Valence. The ethane
# molecule is built from two methyl radicals

# First the two methyl fragments are calculated.
# If the FRAGOCCUPATIONS keyword is used in ethane the fragments should be calculated
# spin-restricted.


AMS_JOBNAME=frag1 $AMSBIN/ams <<eor
System
  atoms
     C         0.019664   -0.034069    0.009101
     H         0.039672   -0.069395    1.109620
     H         1.063205   -0.065727   -0.341092
     H        -0.474230   -0.953693   -0.341621
  end
end

Task SinglePoint

Engine ADF
  title CH3-CH3 built from CH3 radicals,  FULL electron calc.!
  basis
    Type DZP
    Core None
  end
  scf
    converge 1E-6
  end
  symmetry NOSYM
  xc
    gga becke perdew
  end
  Relativity
    Level None
  End
EndEngine

eor


AMS_JOBNAME=frag2 $AMSBIN/ams <<eor
System
  atoms
     C        -0.703210    1.217999   -0.497874
     H        -0.723753    1.252869   -1.598316
     H        -1.746567    1.250049   -0.147169
     H        -0.208833    2.137544   -0.147653
  end
end

Task SinglePoint

Engine ADF
  title CH3 radical
  basis
    Type DZP
    Core None
  end
  scf
    converge 1E-6
  end
  symmetry NOSYM
  xc
    gga becke perdew
  end
  Relativity
    Level None
  End
EndEngine

eor

# Next these fragments are used in the calculation of the molecule ethane, using
# the key FRAGOCCUPATIONS to use an unrestricted fragment occupation for the
# methyl radicals, such that they are prepared for bonding. In the one fragment
# the singly occupied orbital will be an alpha-orbital, and in the other fragment
# the singly occupied orbital will be a beta-orbital, such that the calculated
# Pauli repulsion between the fragments will be small.

# The block key ETSNOCV used here is in its single line form.
# The symmetry must be NOSYM.

$AMSBIN/ams <<eor
System
  atoms
     C         0.019664   -0.034069    0.009101 adf.f=f1
     H         0.039672   -0.069395    1.109620 adf.f=f1
     H         1.063205   -0.065727   -0.341092 adf.f=f1
     H        -0.474230   -0.953693   -0.341621 adf.f=f1
     C        -0.703210    1.217999   -0.497874 adf.f=f2
     H        -0.723753    1.252869   -1.598316 adf.f=f2
     H        -1.746567    1.250049   -0.147169 adf.f=f2
     H        -0.208833    2.137544   -0.147653 adf.f=f2
  end
end

Task SinglePoint

Engine ADF
  title final [CH3]-[CH3], etsnocv activated by etsnocv
  etsnocv
    ekmin 1.5
    enocv 0.05
    rhokmin 1.e-3
  end
  fragments
     f1 frag1.results/adf.rkf
     f2 frag2.results/adf.rkf
  end
  fragoccupations
     f1
     A 5 // 4
     subend
     f2
     A 4 // 5
     subend
  end
  scf
    converge 1E-6
  end
  symmetry NOSYM
  xc
    gga becke perdew
  end
  Relativity
    Level None
  End
EndEngine
eor

# Next densf calculations, to view the natural orbitals in this method, see
# also the the documentation for the densf analysis program and the ADF-GUI.
# Input is the adf.rkf of the molecular calculation.

$AMSBIN/densf <<eor
  adffile ams.results/adf.rkf
  Grid Medium
  End
  NOCV
   Alpha
     1
     2
     59
     60
   Beta
     1
     2
     59
     60
  END
eor
mv TAPE41 nocv1.t41

$AMSBIN/densf <<eor
  adffile ams.results/adf.rkf
  Grid Medium
  End
  NOCV
    THRESH 0.01
    RESTSUM
  END
eor
mv TAPE41 nocv2.t41

$AMSBIN/densf <<eor
  adffile ams.results/adf.rkf
  Grid Medium
  End
  NOCV
    ALPHA
      SUM 1
    BETA
      SUM 1
    RESTSUM
  END
eor
mv TAPE41 nocv3.t41

$AMSBIN/densf <<eor
  adffile ams.results/adf.rkf
  Grid Medium
  End
  NOCV
    SUMBELOW 0.5
  END
eor
mv TAPE41 nocv4.t41