Example: Restraint Geometry Optimization: H2O

Download GO_restraint.run

The restraint does not have to be satisfied at the start of the geometry optimization. An extra force is added to restrain the bond length, angle, or dihedral angle to a certain value.

Example for angle restraint

$ADFBIN/adf << eor
title WATER geometry optimization with angle restraint

ATOMS
    1.O         0.001356    0.000999    0.000000
    2.H         0.994442   -0.037855    0.000000
    3.H        -0.298554    0.948531    0.000000
END

BASIS
 Type DZP
END

RESTRAINT
  ANGLE  3 1 2 125.0
END

GEOMETRY
END

endinput
eor

Example for bond length restraint

$ADFBIN/adf << eor
title WATER Geometry Optimization with bond length restraint

ATOMS
    1.O         0.001356    0.000999    0.000000
    2.H         0.994442   -0.037855    0.000000
    3.H        -0.298554    0.948531    0.000000
END

BASIS
 Type DZP
END

RESTRAINT
  DIST  1 2 1.03
  DIST  1 3 1.03
END

GEOMETRY
END

endinput
eor

Example for dihedral angle restraint

$ADFBIN/adf << eor
Title Restraining dihedral of ethane

SYMMETRY NOSYM

ATOMS
  1.C        -0.004115   -0.000021    0.000023
  2.C         1.535711    0.000022    0.000008
  3.H        -0.399693    1.027812   -0.000082
  4.H        -0.399745   -0.513934    0.890139
  5.H        -0.399612   -0.513952   -0.890156
  6.H         1.931188    0.514066    0.890140
  7.H         1.931432    0.513819   -0.890121
  8.H         1.931281   -1.027824    0.000244
END

RESTRAINT
  DIHED   6    2    1    3     20.00
END

BASIS
  type DZP
END

GEOMETRY
END

endinput
eor