#!/bin/sh
# For property calculations, XC potentials with asymptotically correct (-1/r)
# behavior outside the molecule, the results tend to be superior to regular LDA
# or GGA calculations. This is especially true for small molecules and for
# properties that depend heavily on the proper description of the outer region
# of the molecule. In the example, all-electron basis sets are used. This is
# mandatory for the SAOP potential.
# In the first example, excitation energies are calculated with the GRACLB
# potential. This potential requires one number as argument: the experimental
# ionization potential in atomic units. This number can be either based on an
# experimental value, or on previous GGA total energy calculations.
AMS_JOBNAME=GRACLB $AMSBIN/ams <<eor
System
symmetrize
atoms
O 0 0 0
C 1.128205364 0 0
end
end
Task SinglePoint
Engine ADF
title CO excitations grac potential
beckegrid
quality good
end
excitations
lowest 10
onlysing
end
basis
core None
type TZ2P
end
xc
model GRACLB 0.515
end
EndEngine
eor
# The same calculation with the SAOP XC potential would differ in the XC block
# only:
AMS_JOBNAME=SAOP $AMSBIN/ams <<eor
System
symmetrize
atoms
O 0 0 0
C 1.128205364 0 0
end
end
Task SinglePoint
Engine ADF
title CO excitations SAOP
beckegrid
quality good
end
excitations
lowest 10
onlysing
end
basis
core None
type TZ2P
end
xc
model SAOP
end
EndEngine
eor
# SAOP depends on the orbitals which makes it more expensive to evaluate than
# GRAC for large molecules, but is much easier to use, since it does not require
# an ionization potential parameter as input.