[gpaw-users] On the calculation of van der Waal interactions

[leonardo espinosa]

Dear GPAW users,

I'm trying to include the van der Waals forces in a geometrical
optimization with gpaw (v. 0.10.0) but I'm having some issues depending of
the used approach:

1.  Using the Tkachenko & Scheffler method (TS09): It seems to work OK in
some "normal" systems (those that include C, N, O, H or other organic
atom), however the inclusion of noble metals such us gold or silver in the
calculation produces the next error messages:
 "KeyError: 'Ag' (or 'Au')
  File "/appl/nano/ase/3.8.1/lib/python/ase/optimize/optimize.py", line
114, in run
    alpha_a[a], C6eff_a[a] = self.vdWDB_alphaC6[atom.symbol]"

It seems that somebody had the same question a couple of years ago:
https://listserv.fysik.dtu.dk/pipermail/gpaw-users/2012-May/001436.html
But the solution to the problem was the inclusion of Rn setups. In my case
this does not solve my problem.

2. Using the vdW-DF and BEEF-vdW methods: It seems that by defining
xc='vdW-DF' or xc='BEEF-vdW' is not the way to use these methods. In both
cases the error message seems to point the "/gpaw/xc/vdw.py" in the line
788 (among other lines).
Testing on some organic systems (adenine or cytosine) it seems to work, but
during the run, the input does not read the generated setups for the atoms,
even by adding the lines:
from gpaw import setup_paths
setup_paths.insert(0, '.')

Any help or hint about how to use these corrections, in particular the
TS09, on metal/organic systems will be more than welcome.

Best regards and thanks in advance,

leo

---
Leonardo A. Espinosa L.
Postdoctoral Researcher,
Aalto University,
Espoo, Finland.
http://goo.gl/WjBIXv <http://yonk.is/gI3>
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