Example: sTDA excitation energies wB97: TCNE-Benzene
****************************************************

"Download TCNE-Benzene_wB97.run"

   #! /bin/sh


   # Calculation of the excitation energies of the complex TCNE-Benzene using the
   # simplified Tamm-Dancoff (sTDA) method by Grimme, for a range-separated
   # function. This method is meant for hybrid functionals or range-separated
   # functionals during the SCF. In this example the range-separated functional 
   # wB97 is used during the SCF. In the the calculation of the excitation
   # energies the sTDA method is used in which the required integrals are
   # approximated. For range-separated functional one needs to set the parameters
   # manually. Note that the alpha and beta parameters for sTDA for range separated
   # functionals in the Risthaus paper (dx.doi.org/10.1039/C3CP54517B) are mixed
   # up. A TZP or TZ2P basis set is recommended for this method.

   # For the excitation energies of the complex TCNE-Benzene, charge 
   # transfer (CT) states are important. Symmetry NOSYM is required.
   # The subkey DESCRIPTORS is added to the key EXCITATIONS such that CT descriptors 
   # are calculated. The the atomic distance criterion used for the calculation of 
   # CT_AT was set to 3.0 Angstrom.
   # The sTDA parameters should be set with the subkeys GRIMMEAEX, GRIMMEALPHA, and
   # GRIMMEBETA of the key MODIFYEXCITATION.

   $AMSBIN/ams <<eor
   System
     atoms
        C     -2.274205   -1.398789   -0.000000
        C     -2.274206    1.398791   -0.000000
        C     -2.274506   -0.699551    1.213150
        C     -2.274505   -0.699551   -1.213150
        C     -2.274506    0.699551    1.213150
        C     -2.274505    0.699551   -1.213150
        H     -2.278385   -2.491323   -0.000000
        H     -2.278386    2.491321   -0.000000
        C      1.368996   -0.686302    0.000000
        C      1.368996    0.686301    0.000000
        C      1.379968   -1.434052   -1.220900
        C      1.379968   -1.434052    1.220895
        C      1.379968    1.434051   -1.220900
        C      1.379967    1.434051    1.220895
        N      1.400955   -2.054479   -2.204820
        N      1.400955   -2.054479    2.204824
        N      1.400955    2.054481   -2.204820
        N      1.400954    2.054481    2.204824
        H     -2.276046   -1.246672    2.158733
        H     -2.276045   -1.246672   -2.158730
        H     -2.276045    1.246671   -2.158730
        H     -2.276046    1.246671    2.158733
     end
   end

   Task SinglePoint

   Engine ADF
     excitations
       descriptors
       descriptors_ct_at_rab 3.0
       onlysing
       stda
     end
     Basis
       Type DZ
       Core None
       CreateOutput yes
     End
     modifyexcitation
       grimmeaex 0.61
       grimmealpha 4.41
       grimmebeta 8.00
       grimmepertc
     end
     symmetry nosym
     xc
       libxc wB97
     end
   EndEngine

   eor
