Example: Constraint Geometry Optimization: H2O¶

#! /bin/sh

# The key Constraints can only be used to enforce constraint in a geometry
# optimization. The Constraints do not have to be satisfied at the start
# of the geometry optimization.


# == Example for angle constraint for water ==


AMS_JOBNAME=angle $AMSBIN/ams <<eor

System
    Atoms
        O         0.001356    0.000999    0.000000
        H         0.994442   -0.037855    0.000000
        H        -0.298554    0.948531    0.000000
    End
End

Task GeometryOptimization

GeometryOptimization
   Convergence Step=1.0e-3
End

Constraints
  Angle 3 1 2 125.0
End

Engine ADF
    Basis
        Type DZP
    End
EndEngine
eor

echo "Angle after optimization:"
$AMSBIN/amsreport angle.results/adf.rkf -r angle#3#1#2


# == Example for fixed-coordinates constraint for water ==


AMS_JOBNAME=fixed_coordinates $AMSBIN/ams <<eor

System
    Atoms
        O         0.001356    0.000999    0.000000
        H         0.994442   -0.037855    0.000000
        H        -0.298554    0.948531    0.000000
    End
End

Task GeometryOptimization

GeometryOptimization
   Convergence Step=1.0e-3
End

Constraints
  Coordinate 1 x 0.0
  Coordinate 1 y 0.0
  Coordinate 2 x 1.0
  Coordinate 2 y 0.0
End

Engine ADF
    symmetry NoSym
    Basis
     Type DZP
    End
    LinearScaling
        Overlap_Int 98
    End
EndEngine
eor

echo "Angle after optimization:"
$AMSBIN/amsreport fixed_coordinates.results/adf.rkf -r angle#3#1#2


# == Example for bond length constraint for water ==


AMS_JOBNAME=bond_length $AMSBIN/ams <<eor
System
    Atoms
        O         0.001356    0.000999    0.000000
        H         0.994442   -0.037855    0.000000
        H        -0.298554    0.948531    0.000000
    End
End

Task GeometryOptimization

GeometryOptimization
   Convergence Step=1.0e-3
End

Constraints
  Distance  1 2 1.03
  Distance  1 3 1.03
End

Engine ADF
    Symmetry NoSym
    Basis
     Type DZP
    End
EndEngine
eor

echo "Bonds distance after optimization:"
$AMSBIN/amsreport bond_length.results/adf.rkf -r distance#1#2
$AMSBIN/amsreport bond_length.results/adf.rkf -r distance#1#3


# == Example for dihedral angle constraint for ethane ==


AMS_JOBNAME=dihedral $AMSBIN/ams <<eor

Task GeometryOptimization

GeometryOptimization
   Convergence Step=1.0e-3
End

System
    Atoms
      C        -0.004115   -0.000021    0.000023
      C         1.535711    0.000022    0.000008
      H        -0.399693    1.027812   -0.000082
      H        -0.399745   -0.513934    0.890139
      H        -0.399612   -0.513952   -0.890156
      H         1.931188    0.514066    0.890140
      H         1.931432    0.513819   -0.890121
      H         1.931281   -1.027824    0.000244
    End
End

Constraints
  Dihedral 6 2 1 3  20.00
End

Engine ADF
    Symmetry NoSym
    Basis
      type DZP
    End
EndEngine
eor

echo "Dihedral after optimization:"
$AMSBIN/amsreport dihedral.results/adf.rkf -r dihedral#6#2#1#3


# == Example for Block constraint (with a dihedral constraint) for ethane ==


AMS_JOBNAME=block_and_dihedral $AMSBIN/ams <<eor
System
    Atoms
        C   -0.004115   -0.000021    0.000023 region=b1
        C    1.535711    0.000022    0.000008 region=b2
        H   -0.399693    1.027812   -0.000082 region=b1
        H   -0.399745   -0.513934    0.890139 region=b1
        H   -0.399612   -0.513952   -0.890156 region=b1
        H    1.931188    0.514066    0.890140 region=b2
        H    1.931432    0.513819   -0.890121 region=b2
        H    1.931281   -1.027824    0.000244 region=b2
    End
End

Task GeometryOptimization

GeometryOptimization
  Convergence Gradients=1.0e-4 Step=1.0e-3
End

Constraints
  Dihedral  6 2 1 3  20.00
  Block b1
  Block b2
End

Engine ADF
    Symmetry NoSym
    Basis
      type DZP
    End
EndEngine
eor


echo "Dihedral after optimization:"
$AMSBIN/amsreport block_and_dihedral.results/adf.rkf -r dihedral#6#2#1#3
echo "Bonds distance after optimization:"
$AMSBIN/amsreport block_and_dihedral.results/adf.rkf -r distance#1#3
$AMSBIN/amsreport block_and_dihedral.results/adf.rkf -r distance#2#6