Example: NOCV: CH3 – CH3

Download CH3_CH3_etsnocv.run

#! /bin/sh


# Example for calculation of ETS-NOCV for 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. The fragments should be spin-
# restricted.


$ADFBIN/adf <<eor
Title CH3-CH3 built from CH3 radicals,  FULL electron calc.!

atoms cartesian
    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

basis
H  $ADFRESOURCES/DZP/H
C  $ADFRESOURCES/DZP/C
end

symmetry NOSYM

SCF
  Iterations 2500
  Converge 1E-6
end

xc
  gga scf becke perdew
end


eor

mv TAPE21 t21.frag1

$ADFBIN/adf <<eor
Title CH3 radical


atoms cartesian
    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

basis
H  $ADFRESOURCES/DZP/H
C  $ADFRESOURCES/DZP/C
end

symmetry NOSYM

SCF
  Iterations 2500
  Converge 1E-6
end

xc
  gga scf becke perdew
end


eor

mv TAPE21 t21.frag2


# 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 keys ETSNOCV and 'PRINT etslowdin-unrestricted' are needed in this case to
# to analyze the bonding in a molecule with unpaired electrons in the fragments.
# The symmetry must be NOSYM.


$ADFBIN/adf <<eor
Title final [CH3]-[CH3], etsnocv activated by etsnocv and etslowdin-unrestricted

atoms
    C         0.019664   -0.034069    0.009101 f=f1
    H         0.039672   -0.069395    1.109620 f=f1
    H         1.063205   -0.065727   -0.341092 f=f1
    H        -0.474230   -0.953693   -0.341621 f=f1
    C        -0.703210    1.217999   -0.497874 f=f2
    H        -0.723753    1.252869   -1.598316 f=f2
    H        -1.746567    1.250049   -0.147169 f=f2
    H        -0.208833    2.137544   -0.147653 f=f2
end

fragments
f1 t21.frag1
f2 t21.frag2
end

fragoccupations
f1
A 5 // 4 
subend
f2
A 4 // 5 
subend
end

symmetry NOSYM

SCF
  Iterations 800
  Converge 1E-6
end

xc
  gga scf becke perdew
end

ETSNOCV RHOKMIN=1.e-3 EKMIN=1.5 ENOCV=0.05

PRINT etslowdin-unrestricted


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 TAPE21 of the molecular calculation.


$ADFBIN/densf <<eor
Grid Medium
End

NOCV
 Alpha
  1
  2
  59
  60
 Beta
  1
  2
  59
  60
 END
eor
mv TAPE41 nocv1.t41

$ADFBIN/densf <<eor
Grid Medium
End

NOCV
  THRESH 0.01
  RESTSUM
END
eor
mv TAPE41 nocv2.t41

$ADFBIN/densf <<eor
Grid Medium
End

NOCV
  ALPHA
    SUM 1
  BETA
    SUM 1
  RESTSUM
END
eor
mv TAPE41 nocv3.t41

$ADFBIN/densf <<eor
Grid Medium
End

NOCV
  SUMBELOW 0.5
END
eor
mv TAPE41 nocv4.t41