#!/bin/sh

# First we calculate the charges for a system

# Here we use the dftb engine, but any engine can be used for this purpose


export AMS_JOBNAME=CalculateCharges

rm -rf $AMS_JOBNAME.results

$AMSBIN/ams << eor
Task SinglePoint

Properties Charges=yes

System
   Atoms
      C 0.0 0.0 0.0
      O 1.13 0.0 0.0
      C 0.0 0.0 2.0
      O 1.13 0.0 2.0
   End
End

Engine DFTB
EndEngine

eor

# let us first optimize without charges

export AMS_JOBNAME=DoNotUseCharges

rm -rf $AMS_JOBNAME.results

$AMSBIN/ams << eor
Task GeometryOptimization

GeometryOptimization
   Convergence Step=1.0e-3
End

System
   Atoms
      C 0.0 0.0 0.0
      O 1.13 0.0 0.0
      C 0.0 0.0 2.1
      O 1.13 0.0 1.9
   End
End

Engine ForceField
EndEngine

eor


# Now that we have charges from our previous fancy calculation, let us use them for a UFF geometry optimization
# * The name of the file depends on the engine used (in this case dftb.rkf)
# * The geometry does not need to be the same

export AMS_JOBNAME=LoadCharges

rm -rf $AMS_JOBNAME.results

$AMSBIN/ams << eor
Task GeometryOptimization

GeometryOptimization
   Convergence Step=1.0e-3
End

System
   Atoms
      C 0.0 0.0 0.0
      O 1.13 0.0 0.0
      C 0.0 0.0 2.1
      O 1.13 0.0 1.9
   End
End

Engine ForceField
   Verbosity Verbose
   LoadCharges File=CalculateCharges.results/dftb.rkf
EndEngine

eor

# Finally let us use the charge guessing, by default dftb is used for charge guessing

export AMS_JOBNAME=GuessCharges

rm -rf $AMS_JOBNAME.results

$AMSBIN/ams << eor
Task GeometryOptimization

GeometryOptimization
   Convergence Step=1.0e-3
End

System
   Atoms
      C 0.0 0.0 0.0
      O 1.13 0.0 0.0
      C 0.0 0.0 2.1
      O 1.13 0.0 1.9
   End
End

Engine ForceField
   Verbosity Verbose
   GuessCharges True
EndEngine

eor