#! /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.