Example: Dispersion Coefficients: HF
************************************

"Download Disper_HF.run"

   #! /bin/sh


   # General dispersion coefficients (beyond de dipole-dipole C6 interaction
   # coefficient) are computed with the auxiliary program DISPER. It uses two
   # output files from previous ADF Response calculations. In the example, the two
   # ADF runs are one and the same and the relevant TENSOR output file is used
   # twice.

   $AMSBIN/ams <<eor
   System
     atoms
        H  0 0  -0.8708056087
        F  0 0   0.04619439132
     end
   end

   Task SinglePoint

   Engine ADF
     title Van der Waals coefficients HF
     basis
       core Small
       type DZP
     end
     response
       allcomponents
       alltensor
       maxwaals 8
       vanderwaals 7
     end
     symmetry C(8v)
   EndEngine

   eor

   # Polarizabilities are computed at 7 (imaginary) frequencies between 0 and
   # infinity. The program determines internally the actual frequency values in
   # this range to use. The user only specifies the number of them, thereby
   # determining the precision of, in fact, a numerical integration over the zero-
   # infinity frequency range. A value of 7 is rather low.

   # MaxWaals determines that not only the C6 but also C7 and C8 coefficients are
   # computed. A value higher than 8 would not be recommended, because the
   # available basis sets would be inadequate for higher coefficients.

   # In DISPER calculations the preparatory Response calculation must use the
   # AllTensor and AllComponents subkeys.

   # The calculation produces a file TENSOR. The subsequent DISPER run uses two
   # such files. In this example, both are taken from the same ADF run, copying the
   # TENSOR file to, respectively, tensorA and tensorB. These names are prescribed
   # for a DISPER calculation.

   cp ams.results/TENSOR tensorA
   cp ams.results/TENSOR tensorB

   $AMSBIN/disper -n1 <<eor
   eor

   # The DISPER program needs no other input than just the files tensorA and
   # tensorB, which must both be present as local files. Note the '-n1' flag: this
   # enforces that a single-node (non-parallel) run is performed. The current
   # implementation does not support parallelization of DISPER, because the kid
   # processes may not have the (local to the master!) files tensorA and tensorB.

