# Example: Asymptotically correct XC potentials: CO¶

Download CO_model.run

#!/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.

$ADFBIN/adf <<EOR title CO excitations grac potential BeckeGrid Quality good End XC Model GRACLB 0.515 End Atoms O 0 0 0 C 1.128205364 0 0 end Excitations Lowest 10 Onlysing End Basis Type TZ2P Core None End EOR rm TAPE21 logfile # The same calculation with the SAOP XC potential would differ in the XC block # only:$ADFBIN/adf <<EOR
title CO excitations SAOP

BeckeGrid
Quality good
End

XC
Model SAOP
End

Atoms
O  0             0   0
C  1.128205364   0   0
end

Excitations
Lowest 10
Onlysing
End

Basis
Type TZ2P
Core None
End

EOR

mv TAPE21 CO.t21

# 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.