[Pw_forum] Implementation of Van der Waals Interactions

[Manuel Otero]

I am a new user of Quantum-Espresso (QE) and I am trying to study the
adsorption energy of lithium ions in graphite. I want to reproduce some
calculations from other people (Persson), to ensure that I am using the
right parameters.

In this system the Van der Waals (vdw) interactions play an important role
and I want to know more about vdw in QE.
In her work Persson (Nano Lett., 2012, 12 (9), pp 4624–4628) says that
there are two approacches to include vdw interactions:
- "DFT-D2 approach, which adds a semiempirical pairwise force field"
- "vdW-DF approach, which adds a nonlocal correlation functional that
approximately account for dispersion interactions"
which approach use by QE?

I am using espresso-4.3.2. In my calculations I use:

&SYSTEM
...
  london = .true.,
  london_rcut =200,
  london_s6 =0.75,

and

ATOMIC_SPECIES
 C  12.0107    C.pw91-van_ak.UPF
Li   6.939    Li.pw91-n-van.UPF

I cant reproduce Persson calculations, but I dont know where is the problem.

It is OK to use this parametres with this pseudopotentials?
I have tryed changing the parametres but my calculations do not improve.

QE enables to change other parameters?

Thanks in advance for any help.

Manuel
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