Example: TS reaction coordinate: F- + CH3Cl¶

#! /bin/sh


# With the ReactionCoordinate block key one can specify a reaction coordinate along which the
# transition state is sought for. This feature is especially useful when an
# accurate Hessian is not available.

# This example tries to find the TS for the S_N2 reaction of F^- + CH_3Cl <==> CH_3F + Cl^-

$AMSBIN/ams <<eor
System
  atoms
     C             0.000000     0.000000     0.000000
     H            -0.530807     0.919384693  0.012892
     H            -0.530807    -0.919384693  0.012892
     H             1.061614     0.000000     0.012892
     Cl            0.000000     0.000000    -2.124300
     F             0.000000     0.000000     2.019100
  end
  charge -1
end

Task TransitionStateSearch

TransitionStateSearch
  ReactionCoordinate
     distance 1 5  1.0
     distance 1 6 -1.0
  end
End

Properties
  PESPointCharacter Yes
End

Engine ADF
  title Transition state search for Sn2 reaction of F- + CH3Cl
  beckegrid
    quality good
  end
  eprint
    sfo noeig noovl
  end
  basis
    core NONE
    type TZ2P
  end
  scf
    converge 1.0e-6 1.0e-6
    diis
      ok 0.01
    end
    iterations 99
  end
  xc
    gga OPBE
    lda VWN
  end
EndEngine
eor