Example: Franck-Condon Factors: NO2
***********************************

"Download FranckCondon_NO2.run"

   #!/bin/sh

   # As an example of a Franck-Condon calculation, lets look at the transition of
   # NO2 to NO2 - . NO2 is a small molecule with only three vibrational modes.
   # Putting an extra electron on the molecule will cause a big displacement,
   # resulting in large electron-phonon couplings.

   # In general, the larger the molecule, the smaller the displacement and hence
   # the electron-phonon couplings and Franck-Condon factors. Moreover, larger
   # molecules have more vibrational modes, meaning that the already smaller
   # displacement will generally be smeared out over more modes, resulting in an
   # additional decrease in electron-phonon couplings. This is fortunate, since the
   # number of Franck-Condon factors increases factorially with the number of
   # vibrational modes, making it prohibitively expensive to take more than a few
   # vibrational quanta into account for most molecules.

   # In order to calculate the Franck-Condon factors for Nitrite and Nitrogen
   # dioxide, the equilibrium positions of the nuclei and the vibrational modes
   # have to be obtained:


   AMS_JOBNAME=NO2 $AMSBIN/ams <<eor
   System
     atoms
        N         0.000000    0.000000   -0.016179
        O         0.000000    1.098646   -0.492918
        O         0.000000   -1.098646   -0.492918
     end
   end

   Task GeometryOptimization
   GeometryOptimization
     Convergence
       Gradients 1.0e-5
     End
   End
   Properties
       NormalModes True
   End

   Engine ADF
     basis
       core NONE
       type DZP
     end
     spinpolarization 1
     title Nitrogen dioxide
     unrestricted
     xc
       lda SCF VWN
     end
   EndEngine
   eor

   # We are using an already optimized geometry for the second calculation but in a
   # real experiment one should run geometry optimization first

   AMS_JOBNAME=NO2_minus $AMSBIN/ams <<eor
   System
     atoms
        N         0.000000    0.000000    0.126041
        O         0.000000    1.070642   -0.555172
        O         0.000000   -1.070642   -0.555172
     end
     charge -1.0
   end

   Task SinglePoint
   Properties
       NormalModes True
   End

   Engine ADF
     basis
       core NONE
       type DZP
     end
     title Nitrite
     xc
       lda SCF VWN
     end
   EndEngine

   eor


   # This runscript produces two adf.rkf files containing the frequencies and the
   # normal modes for both charge states. Lets first look at the ground state to
   # ground state overlap:


   $AMSBIN/fcf <<eor
     STATE1 NO2.results/adf.rkf
     STATE2 NO2_minus.results/adf.rkf
     TRANSLATE
     ROTATE
   eor

   rm TAPE61 logfile

